2005 Chevy Tahoe Timing?

I pick up my Tahoe today after it had an oil change and alignment. I get block away and I can tell something is wrong. The engine light comes on and at the stop light it seems like it wants to stall and my normally very quite car is vibrating and trying to keep from stalling. I bring it back to the place and he runs a quick diagnostic and says the error was " spontaneous timing issue" or something to that effect. He reset the light however I got a block away when I left and although it is running fine now the light has come on again. He thought it is a tune-up issue and it needs spark plugs. Favctory standard is 100k and I only have 64k on them. What do you think it could be?