No idea what happened...most cases the hens come to the toms. Perhaps the hen flew down into the field, and the toms went to strut. A few of the gobblers may have been jakes, and usually remain silent until directly in front of hen...

Sounds like a good place, but you should probably move your setup so you're in a different part of the field. Between the toms and hens is always a good bet , but you didn't mention where the toms were roosted. If they were on the other side of the hens, in the woods, they may not enter the field until later in the morning.

I'm aggressive, so IMO I would set up much closer if possible. If you want to play it safe, determine where the birds go after flydown, and get in front of them...