I think it may have something to do with LastPass. I noticed it today for the first time as well. I think when the timeout was happening for the app login, this popped up. When I logged out of my last pass, the banner dissappeared.
Let me know if that works for you. Confirmation would be cool.
Thanks!
James
***EDIT***
Just confirmed that it is - infact - LastPass and they already have an update to fix this issue. Update your apps and you should be good to go.
I did a reboot and it went away when it powered back on, and your Lastpass theory is plausible, as I have had it on my phone for some time, but only recently begun using it. If it occurs again, I will check there first. I think that is the culprit.