Ubuntu opens up a preferences tab unasked.
 

When I start up Ubuntu 14.04 through FireFox after a couple windows (count somewhat random) have opened up I will get a tab for "Preferences" without a window. This all started a couple weeks ago for no apparent reason.

You can just close the tab, but, it just bugs me to have this happening!

How do I quit this from happening ?

All updates to FireFox and Ubuntu have been done.

maybe you should change your preferences to delete more data when you close firefox, and not restore sessions?
you can also try to start with a new profile, does it help?
or with addons disabled?