Had some small hairline cracks develope on my Lexi, but that looks like something fell onto and cracked the roof.
Drill small hole at the ends of the crack, maybe 1/8 inch. Will prevent crack from spreading.
Clean area with mineral spirits, dry. Clean area again with acetone, dry.
Take some Dicor Self Leveling Caulk and force it into the crack with your finger, and spread some around the area around the crack.
Let it dry a few hours, and then cover the crack with a piece of Eternabond Tape.
Will take care of the crack pretty much forever n ever.