I had a bit of a similar situation in NL last week when I didn't check in my OV Chipcard, which I had just bought, before boarding a train from Den Haag to Schiphol.
This was a combination of overloaded bags (no hands), forgetting initially and not having time to go back to the reader (not a barrier) before we set off.
On the train the NS conductor got quite cross and said "rules are rules", and I was anticipating a fine or something, but he did not fine me or cancel the ticket.
He said I would have trouble exiting at Schiphol (without offering any solution).
But in fact there were no barriers at Schiphol so I just walked out (checking my ticket in the reader on the way).
I sort of took the view that as I had paid the fare (a not inconsequential €9.90) and was exiting the country, I was in the right.
It rather soured the end of a long trip through Europe with no ticketing issues at all, with the railways (not NS) earning €120 or so from me.
Maybe next time I'll try harder...