You'll find lots of info on rewinding this type of motor on the rcgroups forum. If it works fine I wouldn't worry ... but if you want to change the number of turns to get optimal kv then it's got to be the way to go.

I wouldn't say you've got what you paid for when you paid more than the going rate for that motor:

http://www.hobbyking.com/hobbyking/s...idProduct=4913

I've not had any from hobbyking with poor magnet potting...but I've only bought about 10 and not the one you got.