Losi Xcelorin 2100kv weird noise?

I just bought 2 used motors, and one of em was a Losi Xcelorin 2100kv. When I turn the rotor by hand, I hear this weird noise.. Best way to describe it is like scratching a wooden table with a hard object. (Use the backside of a pen and you will hear what I hear pretty much.)

Is this normal for this motor?