Ubuntu 13.04
Seeing same in dmesg:
//Snippet:

  39.664739] wlan0: authenticated
[   39.668057] wlan0: associate with 20:4e:7f:20:c8:3a (try 1/3)
[   39.671917] wlan0: RX AssocResp from 20:4e:7f:20:c8:3a (capab=0x411 status=0 aid=4)
[   39.671985] wlan0: associated
[   39.671999] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   44.824943] audit_printk_skb: 177 callbacks suppressed
[   44.824951] type=1400 audit(1382968729.989:71): apparmor="ALLOWED" operation="open" parent=1350 profile="/usr/sbin/dnsmasq" name="/etc/NetworkManager/dnsmasq.d/" pid=1713 comm="dnsmasq" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[   44.877924] type=1400 audit(1382968730.045:72): apparmor="ALLOWED" operation="open" parent=1350 profile="/usr/sbin/dnsmasq" name="/run/NetworkManager/dnsmasq.conf" pid=1713 comm="dnsmasq" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
[   44.881567] type=1400 audit(1382968730.045:73): apparmor="ALLOWED" operation="mknod" parent=1350 profile="/usr/sbin/dnsmasq" name="/run/NetworkManager/dnsmasq.pid" pid=1713 comm="dnsmasq" requested_mask="c" denied_mask="c" fsuid=0 ouid=0
[   44.881590] type=1400 audit(1382968730.045:74): apparmor="ALLOWED" operation="open" parent=1350 profile="/usr/sbin/dnsmasq" name="/run/NetworkManager/dnsmasq.pid" pid=1713 comm="dnsmasq" requested_mask="wc" denied_mask="wc" fsuid=0 ouid=0
[   53.044029] init: plymouth-stop pre-start process (2325) terminated with status 1
[   89.310243] type=1400 audit(1382968774.473:75): apparmor="ALLOWED" operation="exec" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser" name="/usr/bin/lsb_release" pid=2864 comm="Chrome_FileThre" requested_mask="x" denied_mask="x" fsuid=1000 ouid=0 target="/usr/lib/chromium-browser/chromium-browser//null-40"
[   89.311912] type=1400 audit(1382968774.473:76): apparmor="ALLOWED" operation="getattr" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser//null-40" name="/usr/lib/chromium-browser/" pid=2864 comm="lsb_release" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[   89.311953] type=1400 audit(1382968774.473:77): apparmor="ALLOWED" operation="open" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser//null-40" name="/etc/ld.so.cache" pid=2864 comm="lsb_release" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[   89.311965] type=1400 audit(1382968774.473:78): apparmor="ALLOWED" operation="getattr" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser//null-40" name="/etc/ld.so.cache" pid=2864 comm="lsb_release" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[   89.312067] type=1400 audit(1382968774.477:79): apparmor="ALLOWED" operation="open" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser//null-40" name="/lib/x86_64-linux-gnu/libpthread-2.17.so" pid=2864 comm="lsb_release" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
[   89.312082] type=1400 audit(1382968774.477:80): apparmor="ALLOWED" operation="getattr" parent=2838 profile="/usr/lib/chromium-browser/chromium-browser//null-40" name="/lib/x86_64-linux-gnu/libpthread-2.17.so" pid=2864 comm="lsb_release" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0

//EndSnippet

what-killed-plymouth.log to follow after restart.