this happens to me but its a loud squeek when i turn left and happens at low and high speeds when turning. im having breaks changed on Saturday so could be the same case with yours with regards to the humm! its worht a check to see if the alligned properly and things.
however, im hoping the squeek will go with the change. but i will see if they can check the barings too. quite embarrassing around town when tunring left and there is a sound only dogs can hear hehe!!