And then, there is another cause of cracks in gel coat on any molded-out parts. If the initial thickness is over XX number of thousands due to overspraying the initial color/finish coat in the mold, that exterior layer will shrink a tiny bit and show checks and cracks after XX decades. I have seen this all over (!) the cabin and deck of an older Islander sloop. Looked bad, but when it is time to repaint all those get ground out and faired in before the LPU is applied, and will likely never reoccur.
It's most common on sharper form changes, like an edge to a combing or any other place there is a 70 to 90 degree change in surface --- in the mold all of those are sharp inside corners that are more difficult to control the spray amount. Also true of laying up the initial matt and then the layers of cloth in the resin.
I have observed a line of small holes in the gel coated surface of a sharp raided toe rail on an 80's O'Day where there was never any fiber against the gel layer and any later knock with any hard object would chip out the surface and reveal the shallow void (s) beneath.
Strictly IMHO: building parts from molds is an awesome way to produce a complicated (and stylish) finished part with less labor cost in the production phase, but there are also lots of places where a moment's inattention or lack of skilled labor will cause problems -- some sooner and some later.
Given the heavy pressure to crank out hulls quick at the lower end of the production boat spectrum, it's kind of amazing that they hold up as well as they do. Friend of mind used to work at Bayliner for a while and said that because molds are expensive and there was a huge push to turn out hulls, they would routinely remove (physically) "hot" hulls from a mold and immediately start laying up the next one.
At the semi-custom end of the trade, I recall visiting Cascade Yachts and watching workers lay up the hull and then let that boat continue to cure further in the mold while structural parts were glassed in. Small company- one boat at a time.
So, perhaps the cracks in question are not serious. If my boat, I would certainly grind 'em out and fill and gel coat them. Hardest part of the job (!) would be matching the color.