Yes.
The advert viewing arrangement is complex as it depends on the page, the usergroup, the user (your cookie etc), and the advert rotation method for that slot.
It looks as if in your case the adverts start to show, then the software decides that you should not see the ad. Normally this process is transparent, meaning you are not aware of the 'mechanism' because it is normally faster/smoother than this. Here, something is glitched, and you get a fleeting glimpse of an ad. If you don't end up seeing it, you probably aren't meant to see it, as the final result of all the calculations should be the correct one.
If you do want to see all possible ads, then view the site logged-out, for example with another browser if you don't want to alter the settings on your main browser. A second browser is a handy thing to have. They're all free anyway. Firefox, Opera and Safari all all good choices; Chrome if you don't mind Google profiling you (if you use Chrome then Google build a profile of you so they can show you relevant ads all across the web, or whatever else they do with your profile).
Or use one of the spyware-removed versions of Chrome such as Sware Iron.