Summer 2011 60W L-type magsafe-charger white insulation breaking down.

Hello I got one macbook pro 13 in the middle of august 2011, it came with a 60W L-type charger. The problem I'm experiencing is with the adapter's white insulation (the "rubber") which already started to break down after 2-3 months. I have not mistreated it in any way, always keeping it in a seperate pocket in my laptop-bag. Some (note: just some) who got the same models from the same shippment (school computer) have had the same problem or similar. I have also noticed that the white insulation is elastic and not glued or anything to the interior itself, which i belive may be chafing and therefore damaging the cabel.

Does this get covered by any waranty or any of the sorts? Is this a manufacturing defect? Is there any way to get it replaced without paying over 100$ for a new?