I'd get a replacement, I was so close to trying to get a replacement because of mooshy volume buttons but decided it was really minor. But a power button that's stuck should be replaced. IMO
Sent from my ADR6400L using Tapatalk
Agreed! I've seen another thread regarding the same thing, so you posters in here aren't alone. I'd definitely take it back because that button is as critical as they get. I also don't like the feel of my volume up button specifically, but it works and I've convinced myself to live with it. There is no question about it, that some of the units with any manufacturer will be defective and it sounds like you got a legitimate issue.
If you really want to drive it home, take the phone in with the power button stuck.