very good post!
I have experienced this in several forms. I bought a set of calls once from Albert Paul and we all know his calls are spot on when he makes them. When I received them they played very well for about a couple weeks and then all 4 of them went to heck and starting having squeaks, strange high pitches and terrible roll over. I couldn't for the life of me figure out what happened and none of them were ever chalked either. Now, keep in mind, they came from the south, Albert's shop to PA. The season was winter. Humidity and heating sources were definitely a factor. Well several months later I got them back out and noticed they were playing very well again. What changed... I think the call woods had to adjust to the climate changes from their origin to mine. Whats more strange is over time, about one year... they got even better in play and sound and now are as good as a call could ever be.
I also had the same thing happen with box calls from other makers and noticed the season and climatic conditions affected the play and sound but once all my calls had time to adjust in my home,state, weather they seem to come back or bounce back if you will. So I agree with the others. Not un-common.
Lesson learned. When you receive a call don't be to rash and quick to send it back or rule it out as a bad call. Give it time and see what happens. Could just be it needs time to dry out, change/adapt to humidity and climatic conditions. Might have a rock star of call and not know it right away.