Repairing fine cracks

Yesterday we discovered a few fine cracks on my daughter's board. Here's a picture of them, although they're a bit hard to see:
http://www.northcoast.com/~alanmacy/Al.htm

For parts of the cracks, you can't feel them on the surface, for other parts you can. I think they are a result of vibration on the roof rack. They radiate out from a repaired ding.

My plan is to spread a small layer of sun cure on them and either sand it smooth, or put plastic wrap over them so that they cure smooth.

Any tips or suggestions?

That should work; I haven't had any problems yet with cracks propagating through UV-curing resin. Sand it good beforehand, and I suggest skipping the plastic or mylar. It's too easy to trap bubbles underneath, sometimes big ones.