I get short sharp chest pains when exercising that last a few seconds. I have excellent exercise tolerance accept for this infrequent sensation.

Texidor's twinge. Or 'precordial catch'. This is a common, transient knife-like pain that's worse when you breathe in. I believe it's caused by the pleural lining developing a transient fold, and it's relieved by gulping air to maximally inflate your lungs. If it's not lasting, does't take your breath way, or cause you to faint, it's harmless.
Even. At your age, is important to find out your heart plumbing and rhythm are working properly when you exercise. If no evidence of arrhythmia or isquemia then transient pain source will not be dangerous. (lactic acid nerve irritation, chostochondral pain, gastric gas).