My apologies, I was confusing you with another person who was agonizing about his BMW not coming with heated seats and wanting his dealer to retrofit them after the fact. I got the two subjects mixed up.
Of course you are correct, if they don't get warm enough you should have it checked out and naturally it would be covered under warranty.
I can't stand mine on anything hotter than '2' and even then I usually turn it down to '1' after 15 minutes. My wife on the other hand apparently likes having a hot ass because she thinks '3' feels great where-as I don't want my reproductive bits fried so I never go to that setting.