Something a stranger said to me in the sento today.

I was sitting in the bath today when a gentleman came up to me from the other side of the tub and said “Sentaiberi” or “Senta beri”? I’m pretty sure there was a desu ka at the end. He said this a few times, and I gave him a “Gomen. Wakarimasen” and he kinda went “Ahhh. So ka” or whatever, and returned to his bath. What might he have been saying? He said it with a sort of buddy buddy demeanor