I looked under the hood and I can't see an loose wires, and all the soldering seems to be secure...I'm not making this up. It doesn't happen all the time, but when it does I can lay the guitar on my lap, not touch with anything other than my finger, on the pickguard, and make it crackle...maybe I should name the guitar "Casper" for the ghost in the machine.
Thanks, everyone, for giving it some thought.