I don't think they are chavvy as I don't think chavs "do" Gap and as people have said, they wash and wear really well and last forever. My girls use them as "loungewear" now though, rather than going out and about in, as they are so lovely and soft inside.
I think the women's clothes in Gap have all gone very strange lately though - lots of shapeless dresses. Not chavvy, more bag-lady. I still love their little silk camisoles though - does that make me a chav too?