As for extra-small, I used Google Domains to check it, it certainly seems to be registered as of May 16th.
https://domains.google.com/m/registrar/search/whois/extra-sm...
I did some more digging, it appears that namecheap (or another registrar/reseller) squatted it and is reselling it as a premium domain for $190.
I suppose in the most technical sense, it is available, but my assumption was that this was a list of unregistered domains rather than say an AfterNIC competitor. Would it be possible to note in your database which domains are unregistered and which are being scalped?
Also, thank you for your kind words! And wow, I didn't know that people would actually sell lists like this - I was just building something that I knew I would want to use without really expecting anything in return, and I guess a lot of people found it useful too! :D
I think that refers to "extra-small", which is a word in the linked gist: https://gist.github.com/hugsy/8910dc78d208e40de42deb29e62df9...