The only time that I have folded the wing on a Predator was after it went through 8+ midairs. The spar apparently cracked on one of the midairs and it folded itself up into a neat little ball.

I've built 9 Predators over the past couple of years and I have nothing but good things to say about them and TufFlight. The TufFlight guys stand behind their products. Drop them a line and I'm sure that they will make it right.

Just from the sounds of it, perhaps the lexan spar was not sufficiently adhered to the EPP foam. Liberal doses of spray adhesive on both the spar and foam are necessary for a good bond. On top of that, it is a good idea to run strapping tape over the spar joint top and bottom of the wing.

You didn't mention what type of covering you used. Was it ultracote or oracover? That covering is more elastic than Monokote.

Did you take a picture of it before it blew up?