Chances are that you have an odd bit of content that extends ten seconds beyond what you think is the end of your video. This might be on a track not usually in your display -- the image below shows one, very obviously, on track three.
Take note of the { } bracketed region at the top of the timeline. If your ten seconds is at the end of an hour video you would not notice the second extension unless you zoom way in.
If you are seeing vertical markers in an 'apparent' blank space on any track, you need to zoom in because you may have a very short or single frame object there.
Did you get any warning about blank space when you exported the movie?
Also if:-
your timeline range markers are as in Carl's image
and you had Export selected range checked in the export dialog
and, at the warning message about blank space, you clicked Ignore.