I know that people are aware of this quirk, but I couldn't find a bug related to it.
You may not be a steward on en.wiki; stewardship is determined at Meta. Having only one user listed as a steward on en.wiki has caused confusion recently. The list should be all-or-nothing; it can't list all stewards until SUL is implemented, so it should list none of them.
I've always thought this was a database quirk from past versions of MediaWiki, but God knows I'm in no position to know for sure.