It just didn't seem as funny to me. The episode (I watched it again last night, the episode is called "The Honking"). All of the scenes with Bender as a were-car, Fry being upset that Bender never tried to kill him (since the curse was that Bender would try to kill the ones he loved), everthing with Calculon. It wasn't just one thing.
I would still be willing to watch it if it's on TV, but I don't like the episode that much.
As for last weeks episode ("That Darn Katz!"), it was not the best episode this season but I still liked it. I was a little surprised with what they did with Amy at the end, and I wonder how the ending will be dealt with in the future (I didn't say specifically what happened with those two points because I don't want to spoil it).