Interesting, I assume you're using the mouse, and it looks like this has something to do with where your cursor was over the map as the level was first starting up.
Do you perhaps have the "Show Map Intro" option turned off? That looks like it could theoretically be part of the problem. (Just checking to see if there's a reliable way I can repeat this, since I think I can fix it pretty easily for the next release regardless, but I'd really like to know precisely why it's happening first, and ensure it's actually fixed.)