My girls are 4 1/2 and were recently moved up to the class for 5 & 6 year olds. They can both do bridges easily and (to my untrained eye) pretty well. They do several bridges as part of their class & one of my girls is now working on elevating one of her legs for 5-10 seconds to learn to kick over. I have read here that it is not recommended for girls to do bridges before the age of 5. Should I be concerned? Our gym has a very good reputation, but I'm a little confused by this & I don't want to be that annoying parent who questions the coach...