Red/Yellow screen

My friend bought a brand new 15" MBP on the weekend and yesterday during a lecture this happened:


Funny how the pinwheel is the only thing that has the right colour... anyway, the whole system was locked and she had to hold the power button down for at least two minutes before it turned off. She started it up again and everything was working fine... she hasn't been able to recreate the problem since.
She took it back to the place she bought it this morning but they couldn't replace it since they couldn't get it to do it again, which I expected.

All I really want to know is - what caused it and should she expect it to happen again?

She has a rubber keyboard protector over the keys. Could that have caused an overheating issue or something?

?? - That really looks like a video issue whether hardware or driver - ??

Taking that long to power off makes it unusual though. Seems like I recall an ATI driver in the late 90's that when it crashed, I had to pull the power cable to turn the machine off.

Of course, I haven't read or heard about video driver issues like this related to Macs since I've started using them which would lead me to hardware. Am thinking I might keep track of temps for awhile.

Just as a side note, I've had two total system lockups on my now 33 month old MBP, both in the first 3 months of owning it. It could be just a one time glitch, it is still a computer after all.