Congrats, sounds like you had a great trip.
We have both whitetail and mule deer here too and I've seen a few hybrid over the years. Everything I can see in the photos on your buck, from nose to tail, point to mule deer. Seeing how there's both there, there's always a possibility that some whitetail/mule deer action went on, maybe back in Grandma's day or so, it really doesn't outwardly show in him.

Fine deer though and a great trip, that's the important thing.