If you run into any bolts or fixed anchors that appear sketchy, please report it to one of the links below. Please take a close-up photo if you have the chance (more than one if possible). If the bolt (or hanger) is loose, please try to see if just the hanger moves, or if the bolt itself moves.
It is always safe to hand-tighten a loose nut on a bolt, and safe to gently tighten with a wrench, but tightening strongly with a wrench can be unsafe.