There is room sometimes for your own "Don't ask, Don't tell" policy.

Some of the other arguements are compelling:

In my state the Dept. of Wildlife agents would say there was nothing they could do.

Walking away was an option, but if it wasn't eatin' at you, you wouldn't have posted.

Legally, you have a much more viable and obvious infraction only if you take some part of that deer home. That's up to you. Maybe wait a while to salvage the headgear.