They're walking in opposite directions, Clint taking the time, every few steps, to look around and get a better view of his surroundings. He found he was noticing things, details, flaws in the architecture and the like...

As he moves to walk past Kenzi, he returns the smile and a nod. He figures if they know him, they'll stop and ask what's wrong. If not? Likely let him continue on his little walk.