There's a bug in the software where if you set the Secured Lock Time setting to something shorter than the Screen Timeout setting, then the screen only stays on for like 10 seconds. I had my timeout set to 1 minute, then the Secured Lock Time set to 15 seconds so if the screen went dark, I had 15 seconds to swipe it open before it would lock. Worked great on 4.0.4. But on 4.1.1, those settings caused the phone to time out after 10 seconds. Very annoying. I fixed it by setting both settings to 1 minute. The phone locks as soon as the screen times out, but I can live with that. These settings each appear in two different settings panels, but you can find both of them in Settings --> Accessibility. Just set both to 1 minute (or 3 minutes, or whatever you want...just make sure they're the same).