OK…..
Thanks for all the replies.
Let me know tell you "the rest of the story":
After landing, and on ground control freq, the ground guy said to us, "no worries on this but approach control would like you to contact them". I said ok will do.
Had the other guy monitor ground while I went over to approach freq. This controller said he just wanted to clear up any confusion. So I said that I just needed to confirm which approach of the two options he wanted us to fly and initially had not given us that information… that was all. Since we were told to fly the "Z" procedure, he then asked what the dates were for our approach plates. I told him and then his reply was, "OK, you flew the right approach then".
And that was it.
So….. the fact that he said we flew the right approach left me even more confused… and thus the question if we were supposed to know to fly the "Z" if they don't give a specific approach procedure as the "Z" is the primary/preferred approach.
I think pretty much every pilot here would have at least queried ATC on which of the two procedures ATC wanted him to fly just to confirm….and I was simply making sure I was doing the right thing.
Kap