By all means, get it checked. However, one thing I noticed about my new '08 Duramax was the exhaust smell, right from day one. I have been around diesels all my life and this is the strangest smell I have ever "smelled" from a diesel anyway. It has a kind of "sweet, ammonia" type smell, completely different from anything before. What I found out is it is a combination of the new ultra low sulphur diesel fuel, hence no strong sulphur smell, and the new DPF (exhaust filter) system. Standing by a diesel exhaust used to be bad, and would burn my eyes/make me cough. Not so the "new" smell. Although it is not pleasant, it doesn't "take your head off" like the old did. I have smelled an exhaust that did have antifreeze in it, and the smells, at least to me, were close.......although the antifreeze was a bit "sweeter" if that can be said.
That said, "when in doubt, check it out" for peace of mind's sake. Especially while it's still under warranty!
