Pick any one of:
maybe to avoid a bird/cloud/another aeroplane if airborne alert sounded/unable to land for some reason.
maybe to climb if they had descended too low.
maybe a bit of rough hand flying.
Nobody was hazarded. The pilot probably quite rightly felt that an explanation was not due on demand. Sometimes you just have to place your trust in other people, and not try and look over their shoulder at everything that happened. Don't worry, this has not be learned by everyone in Europe either. An excuse for every event inflight is not necessarily due!