2003 Outback gelcoat crack

I just noticed a small crack in the gelcoat of my 2003 Outback. It is right above the rubrail about midway back. I know that we did not hit anything. Could this be caused by the flex of the boat during use. Is it covered under warantee?

Another strange thing I noticed: when the boat is on the trailer it seems to "spread out". The gap at the windshield door is wider when on the trailer than it is when the boat is in the water. Is this norma and can this have contributed to the crack?