So this morning I set up in the corner of a field where a bird has been spotted and that I worked yesterday. After setting out my hen decoy, I get settled in and start my hunt. It rained a good bit last night and the field had a even layer of fog over it. Right about the time I think the birds should start gobbling, I look in the field and there is a turkey about 400 yards in the direction I just came!!! I called loud enough for the bird to hear, but he just strolled on the other direction. Later, around 7:30, a hen flies out into the field. She acts as if she is terrified of my decoy and doesn't calm down until she is about 100 yards away. I had to leave early and on the way back to the truck I see a bird fly out of a tree, and then just about 200 hundred yards later, another bird flies out. This was about 8:10-8:20. Why were these birds still in the trees, presumably on their roost this late in the morning?
They may have been waiting for the sun to come out to dry off. Or if the fog was really thick they might not have felt comfortable on the ground yet.
Turkeys being turkeys
I have seen this quiet a few times. Some on the ground when I think its too dark and some flying down well after sunrise.
The birds may have been waiting to see the hen (you) that they heard.
The weather most likely kept them in the trees longer.
I roasted a bird Friday night and then sat out almost under his tree Saturday and he didn't fly down till about 9am.
Turkeys being turkeys is the best answer.