I'm usually very blase about development, but lots of people have commented on dd2's inability to bear any weight on her legs. She just buckles and holds her legs up like a little frog. She even sleeps with them held up like that (she sleeps on her back IYSWIM). She sits very well and bends and reaches for toys, but doesnt roll over fully. She hates going on her tummy too if that means anything. Anyway, should I be concerned? Or is there anything I could do to encourage her? She is 8 months and 1 week old.