I noticed this poster when it went up last week - it's all over the Metro system. That's a grammar error, there, and not a common one, either. Leveling the -s form to the bare one (he do) is far more common. I wonder if the copy originally started as "Miss Jessie l♥ves Washington". (Cute use of the ♥ symbol, though.)
I pointed it out to a friend Saturday, and she noticed the misspelling... All in all, a poster in need of copy editing.