If the low temps are in the 50's I wouldn't worry. 40's, I'd move them in if it isn't too much trouble. 30's, I'd move them even if it is a bit of trouble. :-)

I have had my Twilight out at night for over a week with some night temps in the 40's. It is putting out plenty of blooms right now with no indication of blossom drop. Tonight and tomorrow evening are scheduled for 31 degrees so I have them in right now.
I think Tsheets has the right approach to this spring time weather.
Bruce

June, July, August night-time temps for me average 50-54 degrees. Cooler nights can easily be low 40s, sometimes colder. As long as there is no actual frost in the forecast I just leave the peppers out to face mother nature. If blossoms dropped below 60 degrees, I would never see a single pepper.

Thank you for all of the replies. I'm going to just start leaving them out ;)