I had this problem with the cable going into the Magsafe connector on my last Macbook, still functional but concerningly wires were visible. On the charger of

I had this problem with the cable going into the Magsafe connector on my last Macbook, still functional but concerningly wires were visible. On the charger of my newer MBP (2009) the cable-plug join is notably bigger/thicker and hasn't given me any problems. I think they've learned and improved.