Chevrolet Repair: Smell from exhaust, rotten egg smell, poppet valves

Question
I just got my truck back from the dealer. Had the poppet valves cleaned. I have been have a rotten egg smell coming from the exhaust off and on for a while now. Is this cause for concern? I am sure the mechanic at then dealer smelled it. I have been told a little bit of smell is normal. Depending on the gas. Is this true?

Answer
Hi Andrew, The best thing to do here is give it a couple of days to see if it goes away. If not then there might be a problem with either the cat-con or the engine running rich. If it doesn't go away contact them and have them recheck the car.

         Mark