[Richard]

Yep. Things shrink in cold weather, well at least my stuff does. Seriously, Newell was very fond of the push on air fitting connections. They are more prone to leakage in colder temps. My standard practice, and that of other Gurus, is when is found leaking, to replace it with a compression style fitting. I carry a whole tray of DOT compression fittings of 1/4 and 3/8 sizes just for the occasion.

If you look at the nylon tubing under magnification where it goes into the push on fitting, you will see that over time a small depressed ring forms on the nylon tubing. That is why the push on fittings leak over time. Cold weather makes the connection between the tubing and the collet in the fitting loose. A quick fix for a leaking push on, is to snip about a 1/4 off the tubing and stick it back in.