Possibly. Not to add insult to injury but I recently had the same problem. At certain RPM's and vibrations I heard what sounded like a bad cat, just like the little platinum pellets were going nuts in there. Thinking for sure it was the cat or possibly the tranny I took it in without even looking at it. Well, I'm glad I have an honest mechanic. It was the heat shield vibrating against the exhaust just below the manifold. He bent it back slightly and voila, noise is gone.

Not to say the dealer wasn't honest with this guy but it's a fact; there are about as many honest mechanics out there as honest car salesmen and lawyers. And since the car salespeople and mechanics work side by side, well, a double negative doesn't make a positive in this case......