Thanks for the notice. I may get around to putting it on - i'm kinda swamped with schoolwork right now.
I can, however, explain why it isn't. While it may be considered a micronation, Sealand is (apparently) currently unrecognized as sovereign by any sovereign state. Thus, my sources passed it over in collecting flags. If i'd known during my first go, i prolly would have put it on.
Again, thanks, i'll keep it in mind.