Gears very sticky since cold weather started

To start in first I really have to wrench the stick. Most other gear changes are not nearly so bad but a little bit sticky. Sometimes changing down into first is fine. Going into reverse fine. With engine off, gear stick goes into first fine.

Has just had third service, no problems. Noticed recently I had to pump the gas a tiny little bit more than usual when starting in first but otherwise this problem started suddenly with cold weather.

It is a relatively new car so did not expect this. I am a complete novice, and trying to avoid a big bill! Do not think warranty will cover this. Car always drives well and I do not push it hard at all. I am off on a long drive today and will see if it improves warmed up. Fluid problem? Help!