I've had mine loosen before, too. But you can feel it "clunk" when you pick it up, even if they're just a little loose. I'm not sure how much it affected accuracy as I wasn't noticing a problem, but I wasn't shooting for groups either. It sure can't help though!
Then yesterday, this thread was on my mind when I was shooting one of mine, and it reminded me to check them again. They were tight, but I found a little play in the key slot screws that hold the Pic rail section for the bipod. That gun has an Elite Iron bipod and the mount covers up the front rail screw. Of course I had the wrench for the key slot screws (in the stock), but for some reason I didn't have the wrench that fits the bipod screws, so I couldn't remove it to access the front rail screw. The bipod had a little wiggle in it because the rail itself was wiggling in the slots. I just tightened the rear rail screw that I could access, and carried on without issue. I found it before I started shooting, and I haven't noticed an accuracy issue prior, so I don't know if there was a measurable effect on accuracy. When I got home I got the right wrench and removed the bipod. Rear rail screw was already starting to loosen up again because the front screw was still loose obviously. I grabbed the manual and looked for a key slot screw torque value but couldn't find one. I tightened them up by feel as much as I thought I safely could and re-installed the bipod.
Out of curiosity, does anyone know of a published torque value for those keyslot screws?