It would likely be better to describe that as an observation than a communication. Even if someone were deliberately trying to convey they were bored via finge

It would likely be better to describe that as an observation than a communication. Even if someone were deliberately trying to convey they were bored via finger drumming, that communication only works in a social framework where we've mutually established a meaning to that behavior. If an alien were finger drumming on a table that would not necessarily indicate they were bored nonetheless that they wanted to convey that they were bored.