No, buying a new disc will not help. The problem seems to be that the connection with how the disc and the hub mate is loose... it's very similar to having a loose hub. I would definitely have your LBS take a look at it, you could develop wear in that area and cause all sorts of other problems. If you are trying to take care of it yourself... then you'll need to pull it all apart and tighten everything. Let me know how it goes!