Is my laptop getting to hot? Graphics Card?

Hello,
I have a decent computer graphics card its a Dvidia GeforeGTX 260m.lately i have been playin games with no problems then about 5 mins later it gets really slow and laggs really bad for proly ten minutes straight then a little later goes away then goes to it again..Is my laptop getting to hot and my graphics card failing?? I have been running it hard..tomorrow ill shut it down for while and soon as i start it up ill playa game and see if it continues. Also one other thing if it helps i was playing a game other day and it exited and i gota msg a min later saying my graphics card failed but recooperated..Never seen it before..ITs only a year old Asus and its a good laptop.