Comment 3 for bug 343553

That's very likely been introduced by revision http://bazaar.launchpad.net/~notify-osd-developers/notify-osd/main/revision/224 where I fixed bug https://bugs.edge.launchpad.net/ubuntu/+source/notify-osd/+bug/341565. I'll add "compatibility"-checks to ease the transition-phase for patched apps.
What happens is that, right now, checks in notify-osd are only done for the correct capability- and hint-names (e.g. "x-canonical-private-synchronous"). But all patched apps still use the old (and non-spec compliant) ones (e.g. "synchronous"). Thus for the example of synchronous notifications/bubbles these now are handled as asynchronous ones and are treated with the 5000ms timeout instead of the 2000 ms one.