It's a wise shooter who prevents problems. I know there are parts of the country where it would be inadvisable to smoke a cigarette, much less touch off a muzzleloader.
I have never seen it get that dry in Missouri, which is where I shoot.
Do what you think is best, but since you have a fire extinguisher available, you might experiment and see if some extra separation between powder charge and the ball patch gives you a smaller group.