Hi all,
I've submitted my site to dmoz and approved, my site got listed in appropiate category. But it can't searched from the search form.

Is it normal?

Dunno...but you're already lucky to get listed. Several categories have been setup by editors favoring themselves then abandoned for years.

Is this a recent inclusion? I have it in the back of my mind that they periodically update their search database, which may explain it.

Try searching with just the domain name. ie mydomain.tld, not www.mydomain.tld

If you are listed you should be able to search with just the domain as suggested.

Example: weareat.com

http://search.dmoz.org/cgi-bin/search?search=weareat