Ghost In Cucamonga Canyon

I'm not sure if this is a ghost story but it is just as unexplainable. One time around 9pm at night when the sun was completely set my boyfriend and I went up to Cucamonga Canyon to eat desert (we were that bored). So we walk the trail and we stop at a huge opening and sit by a small wall painted with a bunch of graffiti. It was pitch black and numerous times my boyfriend tried to scare me and it was barely working. Suddenly he says "What was that!" and I told him "Oh, stop it I'm not falling for that again!" and then he says "No shut up! I'm serious!" So I stay quiet and right away I hear exhaling. One long 4 second deep exhale like it came from a big human male. I thought it was my boyfriend again because he's quite tall so I slapped his stomach and said "That's not funny stop!" but I have good ears, he was no more than 2 feet in front of me, and the chilling part was the the breath sounded like it was directly behind him. Then he said "I swear to God that wasn't me!" So he takes out his flashlight and points the light in the direction behind him and takes out his two pocket knives, giving me one.
We did't see anything but we felt it best we should leave right away so we did. It was a long scary walk through the trail back to the car. He kept an eye out in front of us and i kept an eye out for behind us and held onto his arm so that if either one of us got grabbed the other would know right away. I don't know what that was or where it came from of what we heard but it was creepy. The scariest part was that it sounded like a human because no animal would let out a breath like that, and it sounded like it was very close to us.
If any of you know anything ghostly or creepy about Cucamonga Canyon or around there I'd like to know.