How unusual is it to have the dealers invoice and MSO for a car. I have that for my car, and when I mention the invoice I keep getting asked is that the widow sticker?

I have had MSO's when I bought new cars and paid for them rather than financing them. Had to take the MSO into the license branch to get a title. Most people never see a MSO since the dealer or the bank or loan company take the MSO to the state license bureau to get a title issued with their lein on it. Maybe your state did things differently, or you may be a car dealer that never titled the car.