What is it called when I get a bump inside my cheek or near my gums after eating certain food ?

I get a bump much like a canker sore sort of like. It's on the inside of my chin below my lip  on like the inside and it bumps my gums it doesn't hurt but I can feel it it's not painful it's not sore it doesn't look unsightly it's just a bump but I can feel it fast and it was triggered by the salad that I ate which consisted of coleslaw mix with Vidalia onion dressing and sunflower seeds. for about five minutes after eating the salad the sewer went away is that normal for? Can certain foods trigger something like that temporarily and what is that because it's not painful it's not funky like a canker sore but that's the only thing I can think of that would be a mouth sore. and I'm telling you it went right away five minutes after I ate the salad. Any ideas?