Hitachi 51F510 - Occasional Snapping/Cracking sound when turned off??

My Hitachi 51F510 makes a cracking/snapping sound once and a while when I turn it off. It doesn't seem to tie to anything I do with the TV, it just does it whenever. It made maybe 2 really loud snaps the very first time I turned it off and on and then maybe 6 or so times since then. After it makes this sound it seems to either mess up the red or the blue convergence somewhat. Anyone know what causes this or if it is defective? I have heard that they sometimes do this for a short time but this is 18 days after delivery and maybe getting close to 200 hours of use? It is also somewhat reddish/yellowish on the left side of the screen which also bothers me and I don't think it is right. This is my third TV in a row that may be defective(first one the screen had a small crack,second one, the convergence wouldn't stay/kept drifting) but I will return it if it may be a long term problem. Thanks in advance.