These are the questions:
First, in your jurisdiction, do you have any legal obligations to the pro you followed? You should not take answers to this question from anyone on this forum: ask a lawyer. Even without a written contract, there may be an obligation.
Second, was there any non-binding understanding, written or otherwise? Did the pro talk to you about getting your pictures?
Third, what is your development path as a photographer? One good wedding shoot doesn't make you a pro, and I'm speaking from experience as an occasional second-shooter. Even if you have no legal obligation to the pro, you may still want his help, or the help of other pros to develop. You've probably got a ways to go, and you don't want to have to climb that mountain solo.
As an addendum, this is also a test of your pro's ethics: if you approach him neutrally and say "the client contacted me and wants my photos" (without disparaging his), you'll find out what kind of person he is. If he says "all your pictures are mine even though we never discussed it" then you've learned a relatively cheap lesson about where not to go for your continued development: this guy is not interested in your development at all. If he says "hey, we had no agreement, they're your photos," then you've just established a trust relationship with a good guy, and it might lead to future collaboration and development.