If it had been day 2, and it dropped to 50 for several hours, you may get a stuck fermentation, but a shake and warming back up typically fixes that. At day 11 some temperature fluctuation will not hurt the beer.
Yeah, I agree with Whiskey, you're well into the primary to be too concern with it being stuck. However, since you didn't take an OG you can't be too sure, but hefes tend to be more forgiving than others. Brew on!!!