I was concerned that my extremely full 4oz boston rounds might crack if the PG Nic solution expanded even slightly in the freezer. I just pulled my box of bottles out of the freezer after a few days and checked a few of them - it looks like the PG has actually contracted slightly. There appears to be a bit more empty space than before - this actually might have created a vacuum effect, sealing the bottle against the polycone cap more tightly? Anyway, just figured I'd give a PSA for anyone currently bottling and storing.
Yeah, shouldn't be a problem. In general, without a phase change (like water to ice), heat makes things expand and cold does the opposite.
On a side note, make sure your nicotine is back up to room temperature before dispensing to your smaller bottles if the nicotine has been in the freezer and you are filling the smaller bottles to the brim.
I recently filled and capped 100ml glass bottles with pg/nicotine that had come out of the freezer and obviously hadn't reached room temperature and the first bottle shattered within minutes presumably due to expansion. I took the caps off the others quickly enough to save the rest though thankfully.
Glass also expands when heated and contracts when cold. That's why if you're melting something in a glass... sciency vial object you need to gradually warm if you're bringing to a higher temp and then first let it get to room temp again and then put in the fridge and after a while put in the freezer.
Keep stuff to a room temperature boy/girl :) a bit of patience will not only preserve your glass wares but also your own skin! Glass bottle explosions can be an utter bitch