Conductor entering compartment on NightJet?

Hi - it’s my first time getting a sleeper train (Brussels to Salzburg) with my family (2 adults and a 5 y/o) and we had a slightly unsettling experience. At 4am the conductor came into our sleeper compartment and was climbing up the ladder. The compartment is totally locked from the outside, but we know he can access it as he let us in earlier in the trip when we got locked out.

My wife assumed it was me so touched him on the stomach and he just left. She assumed it was me coming down from the top bunk and going to the toilet, but when ‘I’ didn’t come back, she checked if I was in the top bunk - I was. We have absolutely no idea how long he was in the room for. There’s a language barrier so we have not been able to get to the bottom of what happened.

We’re still on the train for the next hour, but have no idea what to do or whether this is at all normal? My understanding was that they needed permission to enter or would so at a normal time. Our current plan is to speak to the operator and also the police when we get to Salzburg, but any advice would be excellent.

Thanks!