Odor from heated seats?

I have a 2005 Z4 and recently I noticed a very annoying odor which I thought was an oil leak or was told it could be the cabin filter. I changed the filter and just had BMW do the oil change at 75K. Now, I notice that the odor is coming when we use the heaters in the seats. Anyone hear of this or have any suggestions?
-Bob

wonder if the tech had oil on the seat of his pants ? longshot ? when he sat on your seats ? if you smell the seats do they smell like oil ?

or the heating element in the seat(s) is touching a material within the seat that could be causing the odor when you sit in the seat ? my guess, you'll find it !

Don't think the tech at BMW would have serviced my car without putting protective member on the seat? Well, I would hope not? This dealer is very highly rated and they even wash my car whenever they service it. I had thought about the heating element touching something when I sit in the seat, but the passenger seat is on more than the drivers and it doesen't seem to matter which one is on. I just drove the car today and noticed it again, and it does smell like oil on a hot surface?

If it's happening with either seat I'd check to make sure you're not overheating an electrical connection or plastic connector - the seats are independently supplied, but are a pretty high amperage draw.