Since you have the 2016 Chieftain you have the system where the rubber plungers (as I call them) fit inside the spools. When you push the lever inside the saddle bags down the plungers expand gripping the inside of the spools to keep the bags on. If those “rubber plungers” aren’t fully inserted inside the spools they won’t grip the spools and the bag could wobble.Pulled the saddlebag, checked the rubber feet that set on mufflers, everything is intact, checked both spools, they are tight, installed saddlebag back onto the Chieftain, started the engine, the bag sits still as designed. Don't know how it moved into a loose position so it could move, but will keep an eye on both of them from now on.
Thank you all who replied, I learned alot about the saddlebag system and it's anchoring design, and reading your posts! =)