Radar visibly startles. Scrambling around to face her, he says, "Oh, Major Houlihan, sorry I didn't hear you there ma'am -- "

The shot of adrenaline wears off as quickly as it hit, and with it goes his train of thought. All he does is blink for an extra second or two before remembering: right. She asked him a question.

...What was the question?

Never mind. It probably wasn't too important. "How're you?"