I should have chimed in before, but I was experiencing something similar with the screen timeout. I haven't experienced it lately though, so I don't know if something changed or if there was an app that was causing it.
I do know that there was something with widgetlocker that was causing the notification bar to have issues, but the recent update fixed everything. Part of me feels both the notification and screen timeout issue was with widgetlocker, especially since the issues stopped when I temporarily switched it off, but if all of you were experiencing it with the stock, then I'm not sure what it could be. Now my note 8 and note 3 are running widgetlocker and no more issues.