Hill listened closely, not only piecing together what Pepper said, but trying to get a read on how she said it. A natural knack for reading people was what made her a strong field agent, and even if this was Coulson's friend, she wasn't going to rule anything out immediately. So far, though, there was nothing that set off any alarms. The opposite, in fact: Pepper was doing things like recalling small details about the incident, which was usually a sure sign of someone telling the truth. The power of attorney thing was likely either a coincidence or something Stark had done on his own.
From her description, though, the demeanor of the robber seemed... off. I don't know. Can you? That was downright weird. Robbers usually started off with a demand, especially if they were robbing someone on the street. Why would he have flipped when Stark told him he had no cash? Maybe he'd panicked about having witnesses, but if that were the case, why hadn't he taken a shot at both of them?
"And is there anything else you could tell us about the man? What he looked like, how he sounded, anything unusual that sticks out in your mind?"