I'm trying to run with this patch to figure out why we're creating these managers:

diff --git a/worker/lease/manager.go b/worker/lease/manager.go
index b5de658..9e18ba0 100644
--- a/worker/lease/manager.go
+++ b/worker/lease/manager.go
@@ -4,6 +4,7 @@
 package lease

 import (
+       "runtime/debug"
        "sort"
        "time"

@@ -63,6 +64,7 @@ func NewManager(config ManagerConfig) (*Manager, error) {
        if err != nil {
                return nil, errors.Trace(err)
        }
+       logger.Debugf("creating manager %p for:\n%s", manager, string(debug.Stack()))
        return manager, nil
 }

@@ -232,12 +234,13 @@ func (manager *Manager) nextTick() <-chan time.Time {
        now := manager.config.Clock.Now()
        nextTick := now.Add(manager.config.MaxSleep)
        for _, info := range manager.config.Client.Leases() {
+               leases := manager.config.Client.Leases()
                if info.Expiry.After(nextTick) {
                        continue
                }
                nextTick = info.Expiry
        }
-       logger.Debugf("waking to check leases at %s", nextTick)
+       logger.Debugf("[%p] waking to check (%d) leases at %s", manager, len(leases), nextTick)
        return clock.Alarm(manager.config.Clock, nextTick)
 }

I ended up needing to rebootstrap because I upgraded the source tree in the mean time. But logging again and trimming it up a bit I see:
19:30:15.372 ... [128460] wak... (1)  15:31:15.3720
19:30:19.933 ... [2a0960] wak... (0)  15:31:19.9339
19:30:20.652 ... [3de3c0] wak... (0)  15:31:20.6528
19:30:36.085 ... [1881e0] wak... (1)  15:31:36.0857
19:30:36.094 ... [1281e0] wak... (2)  15:31:06.0859
19:30:36.578 ... [1268c0] wak... (2)  15:31:06.5696
19:30:36.670 ... [1281e0] wak... (2)  15:31:36.6708
19:30:45.377 ... [128460] wak... (1)  15:31:45.3776
19:31:06.139 ... [1281e0] wak... (2)  15:31:37.1316
19:31:06.145 ... [1881e0] wak... (1)  15:32:06.1456
19:31:06.573 ... [1268c0] wak... (2)  15:31:36.5645
19:31:06.712 ... [1281e0] wak... (2)  15:32:05.7122
19:31:15.380 ... [128460] wak... (1)  15:32:15.3808
19:31:19.936 ... [2a0960] wak... (0)  15:32:19.9369
19:31:20.656 ... [3de3c0] wak... (0)  15:32:20.6560
19:31:36.194 ... [1281e0] wak... (2)  15:32:07.1841
19:31:36.198 ... [1881e0] wak... (1)  15:32:36.1980
19:31:36.567 ... [1268c0] wak... (2)  15:32:06.5577
19:31:36.754 ... [1281e0] wak... (2)  15:32:35.7545
19:31:45.381 ... [128460] wak... (1)  15:32:45.3811
19:32:06.244 ... [1281e0] wak... (2)  15:32:37.2340
19:32:06.250 ... [1881e0] wak... (1)  15:33:06.2503
19:32:06.561 ... [1268c0] wak... (2)  15:32:37.5508
19:32:06.792 ... [1281e0] wak... (2)  15:33:06.7926
19:32:15.381 ... [128460] wak... (1)  15:33:15.3812
19:32:19.940 ... [2a0960] wak... (0)  15:33:19.9400
19:32:20.693 ... [3de3c0] wak... (0)  15:33:20.6931
19:32:36.298 ... [1281e0] wak... (2)  15:33:06.2892
19:32:36.303 ... [1881e0] wak... (1)  15:33:36.3031
19:32:36.835 ... [1281e0] wak... (2)  15:33:36.8352
19:32:37.554 ... [1268c0] wak... (2)  15:33:36.5540
19:32:45.375 ... [128460] wak... (1)  15:33:45.3756
19:33:06.347 ... [1281e0] wak... (2)  15:33:37.3377
19:33:06.350 ... [1881e0] wak... (1)  15:34:06.3503
19:33:06.876 ... [1281e0] wak... (2)  15:34:05.8762
19:33:15.379 ... [128460] wak... (1)  15:34:15.3791
19:33:19.943 ... [2a0960] wak... (0)  15:34:19.9432
19:33:20.696 ... [3de3c0] wak... (0)  15:34:20.6964
19:33:36.397 ... [1281e0] wak... (2)  15:34:07.3871
19:33:36.400 ... [1881e0] wak... (1)  15:34:36.4001
19:33:36.557 ... [1268c0] wak... (2)  15:34:07.5470
19:33:36.911 ... [1281e0] wak... (2)  15:34:35.9114
19:33:45.378 ... [128460] wak... (1)  15:34:45.3781
19:34:06.453 ... [1281e0] wak... (2)  15:34:37.4451
19:34:06.456 ... [1881e0] wak... (1)  15:35:06.4560
19:34:06.951 ... [1281e0] wak... (2)  15:35:06.9512
19:34:07.549 ... [1268c0] wak... (2)  15:35:06.5492
19:34:15.369 ... [128460] wak... (1)  15:35:15.3698
19:34:19.945 ... [2a0960] wak... (0)  15:35:19.9453
19:34:20.699 ... [3de3c0] wak... (0)  15:35:20.6997
19:34:36.506 ... [1281e0] wak... (2)  15:35:06.4979
19:34:36.511 ... [1881e0] wak... (1)  15:35:36.5110
19:34:36.989 ... [1281e0] wak... (2)  15:35:36.9891
19:34:45.379 ... [128460] wak... (1)  15:35:45.3798

By just doing a sort | uniq -c of just the Manager memory addresses, I can see:
      7	1268c0
     18	1281e0
     10	128460
      9	1881e0
      5	2a0960
      5	3de3c0

so there are 2 managers that are not managing *any* leases. 1 that is managing 2 leases, but only waking up 7 times. Another one that is managing 2 leases but woke up 18 times. One that is managing only a single lease but woke up 10 times (presumably that one is the application lease that should be getting refreshed every 30s).

its still rather surprising to see to managers running that aren't actually managing anything.