You got me thinking, MrsNop. I suppose it's mostly non-verbal. I go ahead and do "x" without consulting with her (seeing if it's 'okay' if I do x). X could be doing yardwork (instead of something else she wanted me to do), taking DD5 on a bike ride, etc. In these situations, I get called to task for not talking with her about something.
I'm a little scattered today...it's taken me two hours to write one paragraph. I'll try to think of some more examples of me being assertive, but right now, my mind is mushy.