I've updated the source of my plugin
and it's not showing as an update for any site that have the plugin installed.
before today, the version was 2.0.2.
I tried updating to 2.0.2a, and when look in the update plugins tool on the WP dashboard, it states: "Newer Version (2.0.2) Installed".
Something is wrong. So I updated it again to 2.0.2b. Still the same problem.