restless & fussy at night all of the sudden?

So .. knock on wood .. my LO has been sleeping through the night since 8wks. Unless she was sick of course. 
She has almost all teeth in, except 4. I don't feel them, but she is chewing on things more. So i know they are coming. The past week, she's been waking up between 1-3am or 5ish and fussy & restless during the night. Not a scream or wimper.. but a fussy cry. Usually last 5min and she's back out. 
She's never been fussy or restless when sleeping. It's caught us way off guard. Maybe it's teeth? Night terrors (I have them and had them bad growing up), or..? Idk. 
Just talking to myself, trying to think what could be causing it all of the sudden. She's a little over 16mo. 
No rude comments please.