[Max Lobovsky]

That is not a problem. All electric motors I have seen make some sorta noise when stalling. (I think they make the same noise at all times, but it is usually covered up by the sound of all the rotating parts.) Some people on my team also seem to be afraid of it thinking something is wrong, but as long as you don't have too much voltage (and consequently current) going through the motor at stall, it is safe.