Do I have a head problem

I'm looking to buy a '90 Honda Civic Hatchback and was checking out the car today. The seller told me that it burns a little oil and i took the oil cap off, with the engine running and it blew out air not so much but it was some. I was wondering if this could be due to my valves or is the air normal. Also could this be the reason that it is burning oil. Also what would be needed to rebuild the top end if that was the problem