Upon my re-run of the show, I've noticed an inconsistency.
In the first season, episode 3 'The Fuzzy Boots Corollary', Leonard arrives home with bags, singing. Sheldon says, "Oh, I hope that scratching post is for you." When Leonard pulls one out. Leonard replies with, "I know what you're thinking, I've taken your asthma into account."
Yet, when Zack (Penny's ex-boyfriend) asks for a sperm donation from Leonard so that Zack and his wife can have a child, Sheldon comes in and makes reasons for himself being a better donor. One of the reasons is 'he doesn't have asthma'.
Am I mis-hearing this or does Sheldon have asthma or not?