what you heard was probably a "put", which is a distress call. they probably saw something they didnt like and were alerting each other. gobblers rarely make any noises other than gobbles while strutting around in the spring, however when fighting they "purr" very rapidly. in the fall, they make alot of the same noises hens make only deeper and raspier. i even hear jakes alot "yelping" in the spring like the hens do when accompanied by the dominant bird. i used to raise wild turkey in a pen and gobblers make a variety of noises that most hunters dont even know about. mine made one noise consistently that i couldnt even tell you what it sounds like but when i do it in the wild look out cause you have one pissed off tom.

EDIT - actually the sound my gobbler made was sort of like a pigeon "coo" in a turkeys voice, that as best as i cn describe it. but he did it while wild birds visited the pen and boy did it piss them off