Oh, 60 seconds? (I actually reduced the normal update notif's duration at some point.) I've never given normal, smooth-working update notifications much importance, so I tend to think that it's not an issue I'd worry about, but otherwise I'm drawing a blank as to what might cause this. Then again, I haven't given it a thought before. All I can say is, even if it's a glitch, it isn't one that I'd care about much (or even notice for a while).
Tend to check whenever I disconnect (intentionally), and after reconnecting, resuming from hibernation, and just randomly, intermittently, whenever I think of it, so as long as the updates go smoothly and I like the numbers and confirmations I see, I'm all Zen about Avast.