If you listen to Lovett Williams Turkey Calling tapes, tape #3 (I think), he has recorded a " hush" call, which he says is used by turkeys in the fall, when the turkey feels a poult has started kee-keeing too soon after a flock breakup. It is a rapid staccato call, kinda like duh-duh-duh-duh-duh-duh-duh or pup-pup-pup-pup-pup-pup-pup. I don' t know if turkeys use that in the spring, but, as S-n-D says, turkeys have many different vocalization patterns, and it is hard to tell what you were hearing.

Option #2, and more consistent with what you have described in you setup, would be a " fighting purr."

#3-another hunter