Minor cracks in the GC are common. GC gets brittle over time. you can grind the crack down to the fiberglass and fill it. Or You can leave it. Either way as long as it's just a surface crack you should be fine. the Cracks will catch dirt and what not. So expect them to get blackened over time. But I've used Starbright Deck cleaner to clean the blacken cracks with some success in the past. As well, once you start looking for GC cracks your going to find allot of them. but don't worry if they are just the normal surface cracks your fiberglass underneath should still be solid...
these guys are in St.Pete, FL
http://progressiveboatyard.com
I'm sure they can give you an est on how much to fix your boat...
Good Luck
L8R
Chris
L8R
Chris