Yea, ESD = Electric Static Discharge, you can pass along quite a bit of voltage with out feeling it, I think it's 75k when you feel some pain from them.
I have found, grabbing the case isn't the best anymore, as a LOT of them have a bit of a powder coating on the inside, and your not grounding your self along with the rest of the parts, you need to be touching bare metal on the case, that or some how the ram seating just wasn't the best.