i know that some heat at the back of the phone is normal, specially when you have a phone made out of 1 piece of plastic, but the overheating issue with the lumia 920 (and others) is massive.
yes, sometimes i do play games or browse the internet for a long time, and sometimes i can't even touch the back of the phone without burning myself (not to get injured but to hurt my fingers).
maybe is a software issue and can be solved by update, but idk if this is the case cause why they didn't solved it with the GDR3 update
my hopes are in laziness (hahaha yes, laziness). they were so lazy that they wanna wait till 8.1 to solve some coding problem and fix this overheating issue
and again, sorry about my english