Renee 350IS

Hi Everyone I'm a Newbie and I just bought my 2007 Lexus 350 IS two weeks ago. I just wondered if anyone else has heard of or had this problem. If I have my radio set on an FM station and I turn on my rear defogger, the radio goes staticky. It doesn't do this on AM or Satillite stations. Any ideas? I took it back to the dealership and they called in their field tech and he hadn't ever saw it either.