Colleague A and a Colleague B had an interaction with each other. It isn't quite office but security and public facing. Colleague B is female, Colleague A male.
Colleague B is bare minimum a Supervisor, there since August via an external Agency, Colleague A is in house there for 20+ years but lower level.
Colleague B is mid 20s probably, Colleague A is mid 60s. I assume intent was quite harmless.
Colleague B walks to and through door, to check on her Agency Staff out searching to check in position, Colleague A says "Here comes trouble" but lightly.
Harmless banter or poor professionalism? I have no plans to get involved.