The Carbon-reinforced plastic parts on the 05R actually have a tiny bit of conductivity. I doubt it's enough to cause a short but who knows? Was your esc solder tabs touching the rear bulkhead stiffener?
i don't recall thay they were touching, but they were certainly VERY close. that actually sounds like a logical reason, because my chassis does conduct electricity on carpet. when i was first running it on carpet during the summer, the chassis would build up a charge and discharge on my servo, this shorting it out. maybe the solder tabs arched to the chassis and to each other?