I have had addons make this happen to me in the past. Usually just updating them will fix it (assuming of course it's fixed by the addon supplier).
I use
WoWMatrix to update my addons and I do it daily.
If you are interested:
Jerry introduced me to WowMatrix. For those of you that don't know what it is, it is not an addon but rather it's a stand alone exe that does nothing more than update the addons for you from their websites (nothing more than what happens when you download from curse or other interface sites). You can check updates and you have the options to update all or update some/none.
If you are like me and have a dozen or so addons plus modules for those addons, it's a pain in the ass to update them all one by one not to mention time consuming. Because of this, my addons were always out of date.
Keep in mind that ANYTHING you download off of the web is potentially dangerous to both your computer and your account. I have lots of friends including myself that use WowMatrix for months without problems. But always make sure that the addons you get are tried and true.
If you are concerned about potential keyloggers (and you should be), then you can always get a
blizzard authenticator which is only $6 and totally rocks!