Flying an offline Campaign, I get a Mission Success message while my aircraft is on takeoff roll.  It has happened each flight so far.  Is this some sort of bug or something else?

Use documentation about options...

So what you are saying is that there is something in my settings that I have to adjust?

On campaign start make sure that

 

1) "No instant success" is ON (in-game difficulty settings)

2) "Primary objectives" is CHECKED (DCG options)