Not sure, I agree with the above posts. Looks like rust to me, in places. If I were you, I would get it into a dealer, "post haste" to have it checked.
Edit: Not sure about your question though. I have never heard of exhaust being covered.
You really don't have to.But it is just a build up of mud and a slight bit of rust.He is in Texas not the east or the pacific northwest. If you don't wheel your jeep much, or clean it regularly after wheeling, everything will start to stick.I do believe if he took it to the dealer, they would laugh and say the same.
Seriously, I first took this post to be rather funny, but has anyone noticed that Mr. Rubidriver has over 1900 posts. No one with that many posts is going to make a mistake like having mud on the exhausts. IMHO that is.
With that being said, Mr. luckrider is the only one in this thread who has had anything to contribute.
err except for the ones who want Mr. Rubidriver to clean the mud off, which prolly needs to be done anyway.