The status page is detecting all packages with a regex on the server, but it cannot correlate it with a package in the index. usually this is when package was previously release and the sourcedebs are still on the server.
There's no automated process for clearing sourcedebs off of the server. We need to manually clear them if needed. Usually we expect packages to be rereleased so don't monitor the yellow lines closely. It's mostly to make sure that we don't suddenly see many unindexed packages.
Tully