I was taught a couple of generations (or more) ago to blow down the barrel of the gun before pouring powder. Sparks can linger a long time. a little extra air will burn them out pretty quickly.
If the patch leaves a thread or such in the bore, that can smolder for minutes.
Addressing the static electricity question, I offer this link:
http://www.ctmuzzleloaders.com/ctml_...ks/sparks.html
Pops