Just checked, and all my messages from before 2005 are also missing from this board. However, if I do a google search for some of the names and subjects I posted about in the earlier years, I get the posts in results from an archive area of the site. I do find earlier messages I posted, back as far as 2000, on other locale and surname boards, so when messages get archived may depend on how much traffic a board gets.
It never hurts to re-post a query if it's not still on the active posts. I sometimes do that after I discover new info about a person that I have not posted about recently.