Has anyone ever had this happen to an AMK?
AMK Heetsheets

I've had that happen too - on the other hand, I think the blanket cost me 20p (30 cents?) on offer, so I bought a few.

I just think of them as being disposable, and throw them when they get old.

(In fact I have mostly switched to carrying disposable ponchos now - much more likely to be useful if I get caught out, same size and still provide a wind / water resistant layer if I need to rig a shelter)