Is $450 to patch a leaking roof a fair price?

I had my roof replaced about 3 years ago, and it's been leaking for the last year. The contractor sent me pictures and said the heat split it open. I asked how he plans on fixing it, and he said he'd get some adhesive and a little bit of rubber to patch the holes and then re-pitch all the seams. I'm unsure if this approach will work.