If it's a new noise you haven't heard before, you should definitely take it
in.  I've heard some with transmission whine, but it's usually not very
noticeable.  I've seen many with worn wheel bearings making a humming
noise.  You could also be hearing the squealers on your front brakes, I
suppose.  If you have it checked, you should know what's happening well
enough to make an informed decision.