Since Star-Lord was more or less preoccupied with locating someone or other in his family, and both he AND Gamora seemed to be getting a little frustrated with his constant complaining, Rocket had decided to slip away to explore this place a bit on his own.
First, he scampered back to the Milano to gather up the rather important flower pot they'd brought with them. Why was it important, you ask? Because it contained the still small, still growing form of his best pal in the universe, Groot.
Now keep in mind that Rocket really had no idea that, unlike worlds like Xandar, people on earth aren't accustomed to seeing strange alien beings just walking around like they own the place. So again, he found himself getting annoyed at the weird looks people were giving him. Come on now... WHY oh why would people be staring at a raccoon walking around like a person, talking and carrying a flower pot? Oh, and with a GIANT BLASTER strapped to his back? Yeah, I can't figure it out either, folks.