My LBS is a long time friend who specializes in Specialized bikes. He works on all bikes and he said the first thing he does before working on any bike is to tighten that screw up. It is common with all bikes and is just a part that needs regular attention. He gives lifetime service with the bikes he sales so I take mine in once a month just for adjustments. He said if I do not take it in that often then check that screw everytime you think about it. Mine has never been loose, but it does happen. Loctite will probably help but I would suggest checking it every once in a while anyway.