Yup, I would have done as you did - tried to find the phone's owner.
I had my cell phone stolen once at a club - a club called Casbah at Easton. Anyway, a day later some guy calls the people on my call list to track me down. Says he found my phone outside the club on the curb (WTF?) and just wanted to get it back to me. I tried to give him cash, but he wouldn't accept it.
EDIT: BTW, I recently found a wallet in a parking lot at the Polaris Mall. Picked up, looked in it, noticed $$$. About the same time, I see a guy jogging through the parking lot, obviously looking for something. Putting to the two together, I knew it was his wallet, and that's what he was jogging around looking for. That's where the dilemma came in: keep the wallet and pocket the cash, or return it to jogging guy. So, after debating it for about a second, I stopped him, asked what he was looking for (and he confirmed that he was looking for his wallet), matched him with the ID in the wallet (so that I wasn't just handing over some other guy's wallet to some clown jogging through a parking lot), and handed over his wallet.