My pad is literally disentegrating. A 7" piece fell off near the grill, above the oil cap. This is the second pad, I think. When I bought the car about ten years ago the pad was in need of replacement, so this current one is about 10 years old. Is this a normal life of a pad?

It looks like I can remove the old pad, but how is it putting a new one on? I'm not sure if the shop that put this pad on did a good job, as some areas of the pad have separated from the hood. Bad adhesive?