Deer go into the rut based on photoperiodism which is basically when there is less light in the day, which is pretty much the same time of the year. Sounds like the buck you saw was just cruising checking things out, kinda like us men when we first walk into a bar. I would say what you saw was a little pre-rut activity, because if you were rattling and the rut was fired up, He would have thought he could come steal a doe because 2 bucks were fighting or he could come dominate another buck because he heard him grunting chasing a doe. Look at the backs of the does legs, when those white glands turn kinda of a dark leather color that means she is ready to be bred and the rut is pretty much on. Try little light rattling notthat head banging stuff just 'tickle the tines" because the bucks are probably out sparring testing the other bucks in the area to see who they can dominate and how much competition they are gonna have Good Luck