If your afraid use a short piece of Romex and put a female receptacle on the TV end, plug the TV power cord into it. Run it inside the wall and put a male plug on the other end and plug it in the the outlet. I wouldn't be concerned about running the original power cord inside the wall though. As long as it is of sufficient size it won't overheat.
FLAT TV Panel hidding cords
I have a SAMSUNG LED mounted VERY close to the wall all wires run thru wall. ALL codes say run electical wire outside(leaving one cable hanging down or move electrical box up behind TV. I am not a electrican but do not see what 3'of tv cord would really cause wires to get hot, Opinions?