I have a 15 year old daughter who is very athletic. She is a cross country runner, and in the high school varsity basketball team. I have noticed on several occasions that her lips were actually purplish, and she looked a little pale. I asked her if she was having any problems breathing, or any chest pain and she said no. She told me yesterday that throughout the year her teammates have asked her why her lips are purple. She is a very healthy young lady, eats well, exercises, sleeps well, and is committed to her training. Should I worry?