I know of one person who is following my proposal who doesn't show up on the proposal webpage.
My proposal is for quantitative finance: http://area51.stackexchange.com/proposals/117/quantitative-finance. It shows 19 people following the proposal (on the side of the page), and the total listed at the top of the page is 19 followers. Yet one user is not listed: http://area51.stackexchange.com/users/89/dirk-eddelbuettel. This makes me wonder if other followers are also not being counted?