What should I do w/ random GSoD?

Put some movies on the hard drive and play them constantly or until it crashes. I would also extend my warranty by getting AppleCare.

you can also run the apple hardware test. http://support.apple.com/kb/ht1509

it may actually show a problem with the RAM.

i would at least set up a support request to get the Apple RAM replaced (if it was Apple RAM) and document the issue.

if it randomly starts to kernel panic (i assume that's what you're calling "grey screen of death"), you can take it to an apple store to request diagnostics be run. the service diagnostic is very thorough and can catch weird problems.

hopefully it was just the RAM. :)

Kernel panics are almost always hardware related. Once in awhile they come from poorly written software, but you were right to replace the RAM.

Apple is also pretty good about helping you diagnose these problems. If you are convenient to an Apple Store, make an appointment with a genius and they'll put it through its paces to see what's causing the problem.

Another tool I'd strongly suggest for your arsenal is Tech Tools. A copy comes with AppleCare or you can buy the Pro version. (If you already have AppleCare but lost the CD, you can download it here by entering the serial number of your machine: https://support.apple.com/techtooldeluxe...)