For starters, keep in mind that in cold weather, it is a good idea to keep your tank relatively full (overnight, at least). This will minimize moisture condensation in your tank.
I don't know if condensation could be so voluminous as to block your filler or breather tube (a big T drop at some point would have facilitated that), but maybe some of our midwest or high plains US members could comment on that. If it is, it would be prudent to add some gas line antifreeze (methanol) to adsorb moisture and insure you don't develop ignition problems. As a Quebecois, you probably know this already, so excuse me if I am saying something you already know well.
Some cars are quite sensitive to the positioning of the gas nozzle in the filler neck, but I have not noticed this in my Milly. But with your temps, perhaps the hoses on the pump are so stiff as to cause a funny positioning. ?? Good luck.