I think you're right. I remember reading a 'bit flips can and do happen' war story about server crashes that only occurred at a client located at a high elevation.
NOAA has a supercomputing center in Boulder, CO that has produced some analysis of this, but if memory serves they also have to deal with some low intensity radiation from the Flatirons formation they're up by. Get enough computers with enough RAM and all bit flip sources start counting.
