I started noticing ads posted before my first CL check in the morning were showing up as visited links, and indeed when hovering over them the ads were not in numerical order as I'd expect.

Looking at my own ad, it appears that after a few days you get a "Renew this Posting" button and can bump your own ad.

Yes...just to keep my place for things I've already have seen, I would open the first post on the list to make it read. But, now I'm finding that a lot of posts are being carried forward so this strategy no longer works. Its kind of frustrating.