We had our pool installed about a year ago. In the last couple of weeks I noted a hairline crack in the Sundek that seems to be getting slightly larger (one picture was taken on February 23. The other was taken on March 5). I know cracking is normal, but does this look like something I should be concerned about? Both the pool builder and the Sundek guy said it's nothing to worry about and that cracking happens, but I'd love opinions from people here. Thank you!