OP, they're not trying to rush you. They're indicating to other drivers looking for parking spots that they claimed the spot (to eliminate confusion), so that other drivers can drive past the person waiting so they can look for other spots. If I see someone signaling ahead of me, I know they claimed that spot and thus I can drive past them as they're waiting to park. They're the ones being considerate. In fact, if you're not leaving, just tell them so they can try to find another space. This only happens in places where there is no parking. People have to circle the lot to find a spot that opens up. Often times, you have to ask people walking to their car if they're leaving. If they're not, it's perfectly fine. If you're leaving, you don't have to hurry. They'll be grateful that they've actually found a spot to park.