I'm in Kauai at the moment and did some flying out on a few hiking trails. When I got back to my hotel I noticed one of my props made a slight grinding sound and turned with a slight bit of resistance. Upon checking it looks like a small bit of sand got into the motor despite not ever crashing it. I pulled the motor and blew it out and cleaned a few specks of sand with a q tip. I popped it back in and it sounds much better. No major resistance and a barely (possible non existent) sound coming from the motor bearing. I'd like to send my phantom up, but am having second thoughts. Upon startup (not actual flying, just idle) all rotors spin perfectly and upon power off they all stop spinning at almost the exact same time. No indication that any motor is experiencing any more resistance then another. Any thoughts? Overly paranoid?