They were probably much colder in the hold of 
whatever airplane they flew overseas in. ^_^

I'd rather have my cels in a room that's chilly 
as opposed to a room that's warm. If we're 
talking room-temperature, it's much more likely 
for the temperature to get warm enough to stress 
the cel than it is for a room to get cold enough 
to stress the cel. 75 F should be perfectly fine, 
give or take 5 or 10 degrees. Drastic temperature 
changes either direction should be avoided in 
general.

There's a difference between what feels too 
hot/too cold for a person, and what's too hot/too 
cold for an object's own good. In this case, I 
probably wouldn't worry; just keep them dry, dust-
free, and hopefully dark.