@ Leslie: You may have defective phone for sure because the phone has only been out since Sept. 16.
FYI. I don't use the power button to turn the screen off, rather, I use an app called Screen Off & Lock (
https://market.android.com/details?id=com.katecca.screenofflock&feature=search_result).
With this app you only have to press the app icon (i have the icon on the main homscreen) and the display shuts off. It's really simple and works great to avoid having to constantly fiddle around looking for and touching the power button .
I don't know of an app that would allow you to turn the display on from sleep and bypass using the power button.
But again, if the power button is loose after only a few weeks that's more of a hardware issue and you should return the device for a replacement.