I hope I am describing the correct part. We recently had a 27' Optimum pool installed and the coping on the top has caps that cover the gaps between the walls. These caps seem to shift constantly from regular use and end up sliding off of the gap between the two wall pieces that they are supposed to be covering. Is this expected behavior and should I just check them after each use to slide them back into place or should these have been attached in a more secure manner? Thanks in advance!