Share your experience!
I'm also experiencing this problem. The first day I had it I just love how easy it is to feel the power button. I just noticed it last week (more than a month since I bought the phone) that it is less protruding. I think it happens in time (that's why they have the Tap to Wake function) but I never expected it to be this soon (1 month is a short time).
I doubt that you press it so many times that it only took two days for it to wear out, so have it checked by the store if the change was really noticeable.
I have the same problem also, i just bought the z2 yesterday, but i noticed that matter when the first time i pressed on that button, that's not a good thing, you have to push harder than the normal push to wake up the smartphone.