3711 is a monster, so it will probably just keep plowing through. With that said though, a 15 degree drop in temp is not a good idea. The yeast may not finish up properly with that big of a drop. Can you move it somewhere warmer? With a healthy pitch, and temperatures in the 70s, my Saison with 3711 is usually done in 7-10 days. I like to leave it in the kegerator for at least 4 weeks before tapping, but it's good young too.