I read somewhere that kids who behave at school, with the sitter, etc. but not with parents are just letting go where it's safe to let go. They save it all up for the people who love them because they know it's safe with their parents to let it out. It's a sign that they know they're loved. An annoying sign, certainly, but ultimately a good sign.
My daughter must know that I love her a lot, because I am the only one she ever throws tantrums with!!
Have to admit though that she is perfectly well behaved 99.9% of the time even with me.
