I think this is it: f.lux keeps the "hue" preference turned on even when pairing fails, and so each time you restart it like this, it will try to make an account. It will tell you in a notifier that it's doing that...but of course you might not jump right up and hit the hue button right then.
We probably should not do this on startup, and instead turn the feature off if it fails... this is broken in the code because we allow you to pair with multiple bridges, and so if you wanted f.lux to control one and not another one, it is hard to show that in the UI.
Then, I think Hue is persisting those attempts forever, even if the pairing is unsuccessful. (The "old" protocol did not do this, so I have an excuse....)
Will take another look at it.