Cold..could not reconnect couplers until heated

I know reconnecting hydraulic lines at a higher temperature than when they were disconnected can be difficult due to pressure from expanding fluid.

But, is it normal to have difficulty (not due to hydraulic pressure) connecting lines at low temperatures?

I disconnected my snowblower chute rotator lines at 0C (32F). Today at -16C (+3F) I could not get the quick connects back together. I could easily depress the centres of the tractor female and rotator male ends in with my finger--so there was no pressure. The retaining balls on the female coupler all retracted easily when I slid back the sleeve. No matter how hard I pushed I could not get the coupler halves to mate enough for the retaining balls to drop in the groove. This was the remote fittings on a DK35 which are at waist height and perfect for applying force.

I ended up heating the fittings with a heat gun and they latched easily. I wonder if the two fittings contract enough that the retaining balls and groove can't line up.

....just wondering if others have experienced this.......

Yes quite normal.
I ran a snowplow truck and often pinned/unpinned the plow.
Always kept a plumbers torch in the cab just to heat the couplings.
Snow, frost whatever tends to clog up the works.
Just don't overheat.