Heya!
I wouldn’t be concerned unless the plants started to show problems. I used to have a few tents in the basement that would reach 16-17C each night without a single problem! Plus it can bring out some colours during flower.
Goodluck with the grow!
Thanks guys, not showing any problems at all I think they are all strong healthy plants, starting to flower like crazy now, i am also using heat mats which seems to keep them comfy on the cold nights.