Whenever you hover your mouse over ANY ui element that causes a display box with a label to pop up, and what's being labeled disappears for ANY reason, the label is stuck and stays there infinitely. Quick fix for this is to open and close your map.

Example: open x menu for slaves, hover mouse over "Follow Me," a larger Follow Me label pops up. press x again, and the slave menu disappears but the label stays.

Also occurs when you hover over floaties for a few seconds, then press q
EDIT: seems to only occur with player bases, this could be related to player base floaties always being there but then disappearing when you deselect the option for them in options