Is it normal to feel a particular person's presence before seeing them?

No you did not feel his "sprit". Yes this type of experience is normal (in that a lot of people have this type of feeling). And there are two possibilities to explain it.

1) You got lucky. This is not as amazing as it seems, because your brain probably has these feelings a lot of times and is wrong a lot of times. It is only the times you happen to be right that you remember.

2) Your brain is playing tricks on you. Your brain can make up new "memories" of things that never happened. You might have seen your friend ... and then after that point your brain went and invented a memory that you were thinking about him before (when you actually weren't). False memories are quite common in humans, there is quite a bit of research on this.

The way to test this is to write down all of the strong feelings you have. Then you can go back and put a check mark next to the ones that come true... and an "x" next to the ones that don't come true. I think you will see that your strong feelings aren't very accurate once you start actually checking them (instead of just relying on your memory).

Thank you very much for your reply. I think you have some good points. I am sure that my brain wasn't playing tricks on me, though, because my feeling that I felt my old friend's presence was accompanied by a bout of nerves and wanting to leave immediately (because I was nervous about running into him after all of this time), but I didn't really believe he would actually be there. But there probably is a logical answer, so thanks again for your advice.

While stranger things are possible, what's more likely going on here is 'information analysis lag.' When we receive new information (see things, hear things, etc.) they occupy space in our mind like a queue, and are processed a bit at a time. But we consciously analyze them out of order.

Here then, you may have seen and met the person, then recalled memories of him yet perceived these things out of order thinking consciously of the memories first, then seeing him. This out of order analysis is what's going on in most supposed ESP phenomenae.

Something at this concert tripped a memory of him. A song? Been there before? Around friends of both him and you? A smell or food memory?

I do believe in serendipity, too.

I get "flashes" of things - like one time I saw a beautiful hood ornament on a car and thought "that's going to get stolen" - sure enough, by the time we got out of the restaurant, it was gone.