tough question because we don't know what's in his head. Could be he didn't see anything or was intimidated? I've had bucks react aggressively and others act like they didn't hear anything. You just never know. This year I called in a nice 8 pt using my own voice sounding like a doe. It worked as he was 60 yds out walking away then he's 25 yds and broadside for the shot. I say try anything if needed when they are out of range and leaving what do you have to loose? It may just work! Post rut, I wouldn't use an aggressive grunt call, more of a meet meet call or soft doe call. You might even get a positive response using a fawn in distress call. You just never know.