Macbook air screen flickering?

I have a macbook air 13 in. and i was playing a game on miniclip (save the sheriff to be exact) and i noticed that there were a few thin horizontal white lines flickering on the edge and minimized the window and changed my background to black and there were still the lines so it's not the site. also for the past few months when i'm watching videos on megavideo and videobb then my computer starts to over heat or something and it forces me to turn it off. could the overheating or whatever was happening have effected the screen or maybe from not carrying it properly (holding it by a corner meaning it strains everything by trying not to bend) (which i try to avoid doing but still do it)? it's only today that this has been happening and you can't even tell that there are lines unless you have a dark background so is this a major thing that i should go to an apple store about or do you think that it should just be fine?