I don't really believe in "hangovers" from a win a week prior. To me, that would mean the players don't play as hard or the coaches don't prep as well, and there's no evidence that's an issue with this team. We saw them take it to Oregon State after an emotional win at Oregon. We saw them go into Stanford and win after a huge win against ASU the week prior and then again, at home, the next week against UCLA. I think "hangover" or "trap game", etc are terms used by media and fans to explain why a game didn't go the way that was expected.
I actually believe somewhat in "trap game". Sometimes, a game is on the schedule where the team is good but public perception is that they're not anything to worry about. (Either a good program with a bad record that is showing signs of pulling it together or a no-name program that is having a very good year.) Catching a team like that the week before a game the team has circled can be tough. Coaches, no matter how much they try to fire the team up, might not break through. Other team comes out more intense, has the talent to capitalize early, and all of a sudden your team is trying to flip that switch and escape what has turned into a dogfight. These "trap games" happen.