Header starts expanded (showing all images) before loading

This is kind of an odd problem that I see on my site (http://www.randycoopermodels.com) but not on the demo site.

When the page first loads all of the images from the header are shown on the screen for about a second, then collapse down into the single header image once the page is loaded.

I've tried to duplicate this on the demo page and it doesn't happen at all. So what's the difference? Why would mine be doing that?