He was planning on taking some time off Avenger-ing, just for a few days at least. And SHIELD didn't always respond to bank robberies but - here Clint was. Because it was his god damn bank hat was getting robbed, and he had heard that on the news so - He was just being a good Samaritan. A good Samaritan who came to the scenes of crimes in progress with a bow and arrows.
Of course - he was now having to talk his way through the police line. "No, I'm the - Hawkeye, with The Avengers? Yeah, no, I don't know Spider - Yeah no, I do. He's on his way- so just let me through, I gotta team up with him!"
Lies. Did a good Samaritan lie? Well Clint figured that they did if they had to lie to get past the cops so they could make their way to the bank, where they could actually help.