Or it could be a stuck caliper. Much cheaper and less serious. If you
suggest anything to anyone who is taking your money, suggest the brake
first. It is easier to check for, easier to fix, and all around less
expensive. Not to mention, I think the more likely culprit. Although
my advice when taking a car to a dealer or mechanic if I don't know
how honest they are, is only tell them the problem, not a list of
possible diagnoses. No reason to give them an excuse to take the wrong
route of diagnosis intentionally just to squeeze more money out of me.
I've had this happen and felt like a fool, but I am sure that if they
were competent and honest, they would have checked the cheaper and
more likely stuff first.