I think that's the hint I needed. 馃槉 You're right that I couldn't tell that certain tiles were unvisited and accessible. I found two in the upper right, and so there's one left, which is probably in a tile that looks like it's unfilled and therefore accessible as you say. (Columns 5 and 6, row 2.)
Edit: That was it! Thanks!
I could use a little hint. I'm at 27/30 rabbits collected in the first area, and I think I've been everywhere on the map, with all four shape doors unlocked, and all of the doors that I could find completed, but there are no rabbit icons or exclamation points on the map to indicate where the last 3 might be. I also have a hard time understanding what the icons on the map mean in general.
