I had the same exact cracks on my IVP. I'm still trying to figure out what
happened.
I painted the plane so I can't point to the paint shop. I noticed it about
two years ago after the first flight. I think it was a bad batch of glass.
I replaced it from the inside of the door. The door came out better
then it was before.
Good luck
Al DeSalvatore
Betties Xpress