Q: iPhone 4 screen with moving stripes

Although my iPhone is fully functioning it's screen keeps turning into moving stripes.

If I block it, eventually the screen turns normal again, Burt after a few touches the problem is back

It hasn't suffered any hazard, so water damage is not a possibility nor have it been dropped.

It might been subjected to excessive heat since I was using Wase and it was fixed to my car's pannel... I livre iniciativa Brazil, it's winter time here, but the sun is shinning!

IiPhone 4

Capacity 28,3 GB

Available 3.5 GB

Version 7.1.2 (11D257)

Does  anyone knows how to fix it???

tks!!!