Baby vomited?

My son is almost 4 weeks old and is ebf. Since 2am he has fed, but not burped at all! It’s now 9:30a, and about 30 minutes ago he projectile vomited. And gagged once after that. I checked and his temp is fine. Idk if I’m not winding him long enough, and he vomited because he had so much air on him tummy, or if it’s something else. I’ve never had this issue with my other child.