I've experienced an increase in the number of shows that have started running a minute or two long. Stargate SG-1 seems to be doing it a lot lately.
Basically, try this: Watch a recording, when it reaches the end, it'll end. Go back and Play it (it should pick up right at the end for a few seconds, if not you'll have to fast forward through). Right at the end, hit display and see if it shows a number near 30 minutes (or whatever) for the current amount through the show.
I've also noticed a LOT of the stations are now pushing their shows back a minute or two. (Presumably to screw up VCR users, etc.)
Most shows I record these days record an extra two minutes before and five at the end...