YES all the time. UGH.
When it gets uncomfortable I treat it with an OTC hydrocortisone cream, which clears it up in a week or so in conjunction with wearing a new clean bra every day.
To prevent it, I will give the undersides a bit of a swipe with my deodorant to help prevent sweating/bacteria under there. *WARNING* though, I use Crystal Deodorant, which is aluminum free and all natural. (I know the deodorant / breast cancer debate is still very inconclusive, but in this instance I decided to play on the safe side.)