What was he suffering from?

Yesterday I was at the beach with a friend. This particular beach was a residential cove, so a smaller beach surrounded by rocks. There is only one way onto the beach, a steep small path in the middle. We were all the way at one end, sitting there for about an hour when all of the sudden I realized there was a man, no older than 30, standing in the rocks to our right. I pointed him out to my friend, asking where he came from. She said she definitely hadn’t seen him walk past us, since the beach was narrow and we had been eating lunch. I kept watching his peculiar behavior as he just stood there without moving for a good ten minutes, staring at the ocean. He then walked up to a bigger rock and stared down to the point he was just at, examining everything.

At first I thought he was possibly distressed and perhaps suicidal, but the rocks in that area weren’t high enough to do any serious damage if one were to jump off. Not only was I weirded out that he had appeared out of no where, but by his behavior as well. I kept watching him until he started to walk towards us.
He approached us, kneeled, and said, “I know this may seem strange, but.. would you mind telling me what year it is?” We both just sat there for a few seconds before replying. I said, “It is 2010.. Are you okay?” His speech was normal and he replied that he was fine.. and walked off. We both didn’t talk for the next minute or so, and watched him walk off. He walked to the other side of the cove into the rocks and climbed one of the largest rocks and stood out looking at the ocean, with the mist splashing up onto the rock.

I’ve never had anything like this happen to me, and I’m still super creeped out. He didn’t seem like he was on any drugs, he was pretty calm and collective, and he seemed to analyze his where-abouts as he walked along the beach. He was wearing normal attire…
Is there any medical conditions associated with this? He was too young for Alzheimers..
So strange!