Have a doubt regarding sudden turn off of my laptop?!

Guys I have an Inspiron 7720 se the thing is I just downloaded bf3 from origin and tried optimising the Gfx settings like changing resolutions etc once I was done I started the campaign I think it was like five minutes my laptop abruptly turned off I mean it didn't even show shutting Down it just turned off :/ now I restarted my laptop it works fine but I was scared that my dedicated Gfx got burned out and that it's running on Intel gpu so again I opened the game it worked with smooth framerate still not convinced I tried my dell gpu hardware test for dedicated gpu it showed the test was successful and it's working normally so my question is is my laptop alright especially my dedicated gpu and any reason for the abrupt turn off and by the way that was the only time it happened please can anyone tell if my lappy is alright !?