Not at all trying to be argumentative, Jim, but the only reason I suggested the muffler gasket could be reused is because it doesn't retain fluids like other gaskets would, and it is a fairly simple setup.
Yeah, in a perfect world, its best to get a new gasket, but this is one of those areas that the gasket
can be safely and successfully removed and reused with no ill effect on the bike whatsoever. In my case, my dealer is over 30 miles away, no local dealers stocked it, and I didn't want to go throught the hassle of ordering this one part and paying shipping costs online that amounted to more than the part itself, and I sure wasn't gonna pay the dealers price for the gasket!
John, in short, I agree with Jim that it is probably best if you can plan ahead and get a new gasket, but you can rest safely in knowing that you can reuse that gasket so long as it is not torn as well. You'll find that in motorcycle ownership there are about as many opinions on a matter as there can be!