This had been happening ocassionally with my sz 1 fluffles which we still use folded over and nippa'ed on my very little (2nd centile) dd now 18 weeks. Recently depite very careful fitting, tucking and ensuring the wrap was properly covering the nappy the leaking has been happening more and more even tho' the nappy isn't very wet at all, and sometimes pretty much fresh on. Seems to happen if she wees whilst I'm feeding her, so when she's lying on her side. We've also been using bimbles (although she will grow out of them pretty soon I think) and it has never happened when she is wearing them so , must be something specific with the fluffle I think.
Wondered if anyone had any solutions as it's really beginning to p me off (if you pardon the pun).