This has been going on for a good few months, and it's never bothered me enough to actually mention it, however I've noticed it's starting to get a little worse, so I'll pose the question to you guys:

When I turn my steering wheel more than 1/4 turn to the right, as the wheel is traveling back to center, there is a sound... like a "boing" of a spring.

Think about those spring door stops that attach to the base molding for the floor, where the door is supposed to hit to keep the door knob from bashing through the drywall. Remember how it sounds when you smack one of those and it springs around for a few seconds going "boinnnoinnoinnnngggggg"? Yeah, it sounds like that.

It happens every time I turn the wheel a quarter turn or more, and the length of the "boing" is relative to how slowly I unwind the wheel. I can't figure this out, though I admittedly haven't put much effort into it. Any suggestions?