I subscribe to all the options above that don’t involve removing material.
Let it rest after travel.
Prime the tenon with ivory soap or beeswax.
Smoke it.
If it is dry, and room temperature and still jammed, freeze it for ten minutes and then try to remove the stem.
If the issue is chronic, then I’d consider removing material... and advise the retailer of the QC issue. I did this with a 2016 Pete Christmas pipe that had a stem in which the button was at a 45 degree angle from the rim of the bowl when the tenon was seated flush and flat in the mortise. Fixed it myself, but sent a note to SPC and Peterson.
— pruss