A guy asking about your whereabout doesn't mean he is interested in you.He may just be curious ..Don't read any meaning to it yet
I believe that a guy who likes you would have either walked up to you, or collected your number from your friend or probably told your friend that he likes you.
Let's look at it this way,let's assume the guy is interested in you and he is discrete about it,he may be coy about his intention if he is a shy guy or if he doesn't want to put your friend in the know.
If this guy asking about you is a one-off,then you don't need to read meaning to it but if he is constantly asking about your whereabout, then I can categorically say that he has a thing for you.Humans only care for the people they love.
My advice is if he is asking about your whereabout constantly, I suggest you walk up to him and talk to him.By doing that,you will know know whether he is really into you or not. His actions afterwards will show you whether he likes you or he is just curious.