Swollen gum after eating. Why?

I recently had my 3 wisdom teeth extracted a week ago, bottom left & the two tops. They are healing just fine and everything.. But it seems after I eat something now, food is getting stuck in between my top right muller tooth that irritates my gum causing it to swell. It feels like food is inside my gums, but after I brush the food away it relaxes and goes back to normal.. But you see how is the food irritating my "One" gum now.. when it's never done this before? I have no reason why all of a sudden it's doing this..