Teething or more serious?

my daughter is 2 this month and everytime after she eats anything she gets this rash on her chin. it doesn't seem to bother her in any way and is completely fine in herself. originally I though maybe an allergy to something she was eating but it doesn't matter if it's crisps, pasta, cheese, yoghurt, fruits or veg it always happens. this morning she had a toast and banana, it happened, then for lunch a ham sandwich, crisps and an Apple, happened again, and tonight she had a quick dinner of nuggest and chips then 2 yoghurts. could this be due to teething although it's only when she eats, although sometimes when she has had loads of saliva and her dummy in this happens. Teething or something more serios? any help?!