I'd also make sure you are not flooding the engine when warm. Cold engines need to be very rich (wet with fuel) because they do not vaporize gasoline well. Hot engines do not need as much choke because the hot surfaces vaporize the fuel very well, creating the correct mixture. Try restating the engine without the choke, immediately after landing. This should tell you if the carb is drawing fuel at idle with a hot engine, and if the low end needle is close enough to correct for starting.