Rash from Seventh Generation Pull-ups?

Anyone's LO get a rash from 7th Generation brand pull-ups? My son just potty trained last week and I bought pull-ups just for nighttime and got 7th Generation. We've never used their diapers but have used a lot of their other products (cleaning products, dish soap, etc.) and have always been pleased. Yesterday, I started noticing a little rash on his tushy, a few noticeable red bumps. Today, he told me his tushy was really itchy and when I looked, there were a lot more red bumps. At first, I was totally confused, wondering how he would suddenly get a diaper rash now that he's out of diapers. Then I remembered my SIL telling me her son got a rash from 7th Generation overnights (he uses their regular diapers with no issue) and realized it could be the pull-ups. Anyone else experience this?

Rash from Seventh Generation Pull-ups?

I have been using seventh generation diapers and overnights since the girls were born, never had a problem. Haven't tried the pull ups but the other two don't give them rashes.