On my 1988 car I noticed the follwing on using the (manual) choke:
for a cold start I pull the knob left of the steeringcolumn, the engine starts on turning the key.
I keep it running for about half a minute. When I push the knob back, it comes up again (it springs back up).
Only after a longer time the knob will stay in a pressed down position.

Is this normal and as-intended or is there any unwanted friction in the cable or choke valve??

(I did not notice this before, that's why I ask.

Thank you.

I have noticed this on my CVT 340 also. It should not happen, I don't think it will affect the running of the car as long as the choke is not activated. It's probably the switch for the light a badly adjusted or positioned or choke stop/lever needs adjustment. I assume the issue is at the carb end.