No problem glassing in 60 degree temps. Actually the resin will cure in any temperature with catalyst in the Polyester resin. The UV resin will cure in any temperature as well, as long as it's sunny enough to activate the curing. If you can see your shadow the UV resin will cure.Epoxy resin likes to be above 70 degrees but will cure in any temperature,  just takes longer when it's colder. You can heat up the resin and the blank to make glassing easier in temperatures below 70 degrees.