Yeah, that's electrolyte fluid. Good thing you're recapping this thing now and not later, the electrolyte leakage does more damage over time. Be sure to clean it properly off, use a toothbrush and some isopropanol alcohol to remove the goo.

This might have happened to the logic board as well, and those old-batch SMD caps leak even more goo all over, and it's quite stressy to repair traces if they're broken -- especially if it's a multilayer board (which I think it is).