Did Jiraiya meet Naruto by chance?
It probably depends on how far you are with the series:


  Jiraya knew who Naruto was from the beginning, Minato talked with Jiraya and made him his godfather, he also told Jiraya they are going to name him Naruto. So he knew about Naruto and watched over him from birth and started training him later on.  



They didn't meet by chance, he already knew about Naruto and the seal, he knew about the 4th's seal, that's how he knew it had been tampered with by Orochimaru.   
I think this is the case, Jiraya said he was getting research for his book, but I think Jiraya, being his godfather, tracked him down to begin his training.