Charlie...very nice work on the boat!
As for the US Composites epoxy and blush. I've used US Composites on about 15 boats now and I've seen some blush. It happens most when the epoxy cures in a cool humid environment. I get alot of it in the winter months when working in my shop that will only heat to about 60-65 degrees with a gas heater. As for what it looks like, if you hold your head right you can see it, its an oily look on the finish. Its easier to tell if you have it by rubbing your fingers over the cured epoxy, if it feels oily or waxy there's some blush. Its VERY easy to remove with a scotch brite pad and warm water. Its easy enough that if I wait until a complete cure before apply another coat, glass, etc... I'll scrub it down. You can also tell if theres blush if your sander pads are gunking up quickly.
Again, great work.
Brad