There are a lot of things that could be causing it, as you can tell by all the responses! It seems like my son got a little bit of redness when we switched to cloth. I don't know why but it never bothered him so I didn't worry and it only lasted a couple days.
Yes, it could be an allergy to suedecloth but I suspect that would be a really obvious rash. Its possible though. I don't know what your daughter's rash looks like.
It could be the detergent but like you said, I don't know. I don't think 7th generation is one of the best detergents for cloth diapers but its also not the worst. I like the list at pinstripesandpolkadots.com Do you have a top loader or HE? For top loading I like using purex free and clear, regular tide, or Arm and hammer essentials. Now that i have an HE machine I use allens naturally and/or a homemade detergent (equal parts borax, washing soda, and oxy clean). The homemade one worked well for top loading too. I used 2 TBSP for top loading and one TBSP for HE. All free and clear is good for an HE machine too. I have heard a lot about Charlies. Some kids get a severe rash from it, others don't. That made me hesitant, though.
I'm trying to think of what else could cause the rash. It could be something in food but that seems too coincidental that it showed up when you switched to BG.