I just got my PX-5S and the B-3 key feels a little lose, like it's not as weighted as middle C or A-3 on either side. It's driving me crazy. I know the keyboard has the graded hammer action where the keys are supposed to get heavier the farther down you go, but this seems a little off to me. I'm trying to determine if it's a manufacturer defect, if they're all like this, or if it's just mine. My mother has been playing piano for several decades, and I got her to check it out as well. She confirmed that I'm not losing my mind, although she said it's just barely noticible even to her. Has anyone else noticed anything like this?