When people are looking for friends. Someone told me it was rude that a person I just met left after 20 minutes. They say at an hour is courteous unless something horrific happens.
(It may be worth noting that I look female, this person is male, and we exchanged contact info before I mentioned my boyfriend later in the conversation.)
It's been several days and no contact.
If there is no contact after a week i would say there is no future relationship with said individual. Dont worry about specific amounts of time so much as quality of the interaction. It's ok to have one of experiences with people that don't ultimately lead to a friendship.
Did you just randomly meet this person at the park or was it prearranged in some manner?
Then they were probably just being polite and enjoying your company. It's not a bad thing, and I'm sure they enjoyed the time meeting you. But I wouldn't expect to ever hear back from them. Not every connection will be permanent, but that doesn't mean they didn't matter.