You're not a brat. I think that's a pretty normal response.
I'm no more patient with that crap now that I'm a few weeks away from having a kid than I have ever been.
****, it was all I could do to not call my niece a brat in front of her father (BIL) and grandmother (MIL) Saturday night. I had to settle for telling her NOT to jump on DH's head because she could hurt him.