Is acoustical texture in HVAC ducts an asbestos concern?
Chances are slim that your texture contains asbestos, but you'd have to mail a sample to a testing lab to be sure. It was outlawed in texture in the late 70s, but it wasn't terribly common for that purpose. Follow a safe procedure if you do so. 

It's normal for texture to show inside ductwork, etc. The walls and ceiling are sprayed before the vents are installed, and no effort is typically made to prevent overspray. The little bit of texture that's disturbed when you remove a vent isn't much of a concern. You could simply vacuum it up when it occurs.