@gcrogers, please just take into account that
Avast main GUI -> Settings -> Status Bar -> "Virus definitions version"
is NOT working correctly (there is a BUG).
That means, as other users in this same topic are confirming (and in other topics too) , if you happen to miss one database update, the tray icon of Avast won't display any "exclamation mark", so "your system is SECURED" will still be the tray status.
The main GUI will indeed show that your database is not the latest, but not the tray icon (as it should, according to that BUGGED setting).