I don't know why I thought it was a Savi's. I thought Obsidentify had identified it as such but I ran it through it again and now it's basically inconclusive because I have two consecutive shots of this bird.
Obsidentify says:
Pic #1 99% sure it is a Marsh warbler.
Pic #2 with just a bit of a different head turn: 71% Reed warbler and 29% Marsh warbler.