Hmmm yes can only agree with Oz and Amber. Punishment can only be effective and seen as such if the recipient knows what and how they are being punished, had you known it would not have been any less unpleasant i am sure, but you would have understood and hopefully taken your lesson from the said punishment.

Much more likely is Oz's explanation something came up, discourteous not to call you or let you know, agreed you ought to see how things go and look for any patterns, rather than be unduly concerned right away.

If a pattern does form or you become or you are still uncomfortable or uncertain you should ask permission to discuss and be open and honest with your master, but this is hopefully not going to be necessary.

I wish you and your master all the best, good luck.