Pushing hand with someone who just passed by

Today, I practiced at Bayview Hill Community Centre. Someone who passed by where I practiced asked if we could push hands. He said he hadn't done it for a year of so. We started with one-hand push hand, I noticed he was expecting us to go back and forth. I normally don't practice that way, I actually wasn't sure what I was supposed to do, and I just put my hand up, and didn't move much while he was trying to push it somehow. I did notice that my upper arm and shoulder muscles got tired and sore. I asked if we could just do the free-style moving step push hands, and then we started doing that. No one fell down or anything like that. I tried to move in, but I wasn't able to as his hands were just moving all the time. I was distracted by them. He pushed me a few times quite hard in a straight forward fashion, and I was pushed backward a bit. I felt that I was able to brush him off sideways once, and that was it. I tried to get under him, but wasn't successful. I was happy that he was more out of breath than I was at the end.