For updates that are not "life-threatening" I usually just push out that one file without committing a whole new version of the plugin.

That way the people that have downloaded it before my push, won't know any better and the people that download the plugin after the push will have the "feature" without even knowing it.

Mostly I update my plugins once every 3 months minimum and now with the development cycle of 2 months for a new WP version that will become every 2 months minimum. You need to at least show that your plugin is compatible with the new WP version right?