Luke 1:18-19 NIV84 and Luke 1:34-38 NIV84

Why is it that the Gabriel shut Zechariah down when he was questioned about the prophecy?
But when Mary questioned Gabriel was straight and simply answered her question?

Are we to believe that Zechariah was disbelieving when he asked and mary was simply inquisitive? That doesn't pan out because it gives no indication of that.

If we are to simply believe that Zechariah was disbelieving and mary wasn't, it's just as easy to believe that Gabriel was just playing favorites like a normal man.