  Axions and similar very weakly interacting particles are increasingly
compelling candidates for the cold dark matter of the universe. Having very low
mass and being produced non-thermally in the early Universe, axions feature
extremely high occupation numbers. It has been suggested that this leads to the
formation of a Bose-Einstein condensate with potentially significant impact on
observation and direct detection experiments. In this note we aim to clarify
that if Bose-Einstein condensation occurs for light and very weakly interacting
dark matter particles, it does not happen in thermal equilibrium but is
described by a far-from-equilibrium state. In particular we point out that the
dynamics is characterized by two very different timescales, such that
condensation occurs on a much shorter timescale than full thermalization.
