Is this unusual??

I have never seen a sign like that anywhere

no I have never heard of that, I think you need someone else in with you, so you have a second set of ears to hear what the doc says.
Maybe next time your dh should say now since you won't let my spouse back her would you go talk to her she has questions.

This is very common in my area of Tennessee, esp the rural areas. You will sometimes have a whole family come into the office with Mom or Dad. It comes to the point where you are taking care of the whole family while the actual patient gets neglected.
The easiest way to address this is to have your husband tell the physician that he would like you in the room for the initial part of the visit. Health and well being is a team effort in a family. Most physicans will have no problem with you coming in. Please assure him/her that you have no problem waiting in the lobby anytime there is some discretion needed (mole removal, prostate exam). I am sure this sign is to dissuade the multitude but not the well meaning.