About an hour ago, I got bored so I decided to give a half effort attempt at meditation with no real goal in mind. I was focusing on my breathing and all of a sudden, the air I was breathing in, got cold (not freezing, but still cold) then I could feel it on my upper cheeks. The more I focused on this feeling, the colder it got. Almost freezing. When I stopped meditating, the air got warm again. I got up to check the temperature and it was a warm 71 or 72 degrees I can't remember. Why did this happen?