Rash around toddlers mouth?

I have fraternal twins, 21 months. It seems after I wipe their faces after breakfast or a meal they get a rash around their mouth (little red bumps) they do seem to fade over a few hours. Months and months ago I thought they were getting binky rashes so I took all the right steps and it turns out it wasn't the case. I use a damp washcloth to clean them after meals, I use special washcloths that get washed in their hypo-allergenic detergent (I do put them in the 'bleachable' load to sanitize them, but when thats done I put the washcloths in the baby laundry-so any bleach is washed away). I thought it might be the washcloths (100%cotton) but I have seen this with dry paper towels, too. They don't have an appointment with the pedi for a few months, and I don't think its worth going in for right now, just wondering if you have ever seen this or had any ideas? Thanx!