I agree with JimG and Joe 5859.
My priest usually says the prayers all in Latin, and he’s quick, so I don’t always catch all of it, but I trust that he knows what he’s doing. Also, I’ve also noticed that sometimes he says the prayer of absolution while I’m saying my Act of Contrition, so it can be difficult to hear/notice it sometimes. Thankfully, he usually additionally says, “Your sins are forgiven; go in peace,” in English. But, as I understand it, it’s not really necessary since he’s already said it in Latin.
It’s likely that you just didn’t catch it because it was phrased slightly differently or because of the accent, or he said it in Latin. If it’s really bothering you, you could respectfully ask him about it outside of the Confessional (make an appointment if necessary). If it still bothers you after that, then perhaps you should consider going to another Confessor and mentioning it to that Confessor.