It may not yet be a virtue, but only a formal quality, or simply a beginning for something greater, like respect or gratitude.
Politeness may be the first of the virtues and, perhaps, the origin of all virtues, for it is before morality, or rather, morality begins by being mere politeness, with submission to instituted rules and normative games.
Politeness is not everything, it is almost nothing, but good manners precede good actions and lead to them.
"It is by practising righteous actions that we become righteous." Aristotle.