I do that microwave thing too, but always stop it at 28 seconds, my alarm's always set at a certain hour & 28 minutes, when I bid on stuff on Ebay my maximum bid is always whatever £££ & 28 pence...
I've counted letters in words & sentences since I was a kid, when I was sat at my grandads death bed 6 years ago I repeatedly counted the letters on his hospital wrist tag, which added upto 28, and that number's always stuck and bothered me for some reason.
I'm use to it now & don't even notice I'm doing it half the time, fuckin pain in the ass reading books or watching sub-titled films though.
Got a really annoying teeth brushing ritual as awell.