I've noticed this as well before. Another thing I have noticed is the change and the sound of your calls. Presure can change the tone of a call, everyone has been out and just one day the favorite call just don't sound the same as it did the last time you used it. You start to thinking its you and the way you seem to be running it. Wrong! its the presure change that changes the sound you get. At this time change you call to a higher pitch, or Lowwer and see the difference. I beleive the gobbling is the same, and the gobblers get the same effect
...BT