Skins4SB:
You are correct. Here is where I got the Skins' team data for this year:
http://www.nfl.com/teams/stats/WAS
It has zero defensive TDs and zero return TDs - which I misinterpreted as special teams TDs. But if you add up the TDs for the Skins in their 4 categories, you'll find that there is one more in the team total and that is the one from the blocked kick.
Sorry about that.