We attempted to implement a fix for these recurring, but it seems the solution wasn't perfect for all users. The fix implemented should have dismissed it when you hit "not now" based on a cookie preference. Every time you clear your cookies it will reset the saved options. This is something we're looking to amend so they don't pop up as frequently. If you don't manually clear your cookies, your browser may be clearing them for you, or you may have a corrupted cookie... either way there are lots of potential paths towards resolution. We're currently working on the resolution which will cause you the least amount of work and not be cookie dependant.
In the interim though if they are annoying you. We recommend clearing your cookies once, and then dismissing the message once, and it should set until you or your browser clears those cookies again.