Based on what you have written, I do not think that the lady meant your child any harm, otherwise she would have done it without you knowing. She probably became too at ease with you and maybe she also has a daughter that she misses at home. Having seen you around often might have made her comfortable, thinking that you already trust her. However, we still have to instill in our children's innocent minds that it is never safe to go or even talk to strangers wherever in the world we are.