The fan really shouldn't be running for 4 full hours, but it shouldn't hurt it to do so. If it really bothers you, turn it to a position between the auto and on. It should shut down then. You could also check on the side of the furnace, on the electrical pipe, there is sometimes a switch installed which you could turn off. That's about all I can think of. I wouldn't worry. If you can't call till tomorrow that's the best you can do.
40 + years of home building, remodeling, repairing and maint.