In the episode where Peter gets liposuction, he's waiting in line at the food store, with his newly thin body. There are points where you can see the arms on his glasses, like he's wearing them, and at other times, there are no glasses. This happens through the episode, but this part really stands out.
Yeah right after that while he's walking up to the register you can still see the bridge as well as a little "bleeding" of the skin tone of where they were covering up the glasses