At the climax of Paul, as the protagonists wait for Paul's people to arrive and pick him up, a helicopter arrives carrying the film's main villain, the Big Guy (actually a woman, played by Sigourney Weaver). As she steps off the helicopter, she remarks,
Small world.
This implies that she's met the protagonists before, but this is the first time she's appeared in person in the film. My first thought was that she was the café owner from near the start of the film, but that's Jane Lynch's character. My current thought is that it's a reference to something, but TV Tropes doesn't include it in the film's list of Shout Outs.
Why does the Big Guy say "Small world" when she first arrives?