The temperature spike during Netflix use is normal. As far as the thermal compound goes, generally Apple uses cheap compound and it's usually applied very poorly and this makes the heat problem worse. Being that you are under warranty, I'm a little hesitant to recommend re-applying the thermal paste as this isn't a user friendly repair/ alteration. But I can tell you that using Arctic Silver 5 and applying it correctly made a -6C difference in my Macbook. I was not covered by warranty so I went ahead and did this myself, but I can't recommend you do this and void your warranty in the process.