An important question, since you're so new, is if you were actually in a submission when you tapped or where you just tapping because you were terrified/exhausting/extremely uncomfortable. Because if you were in a sub, he probably just didn't notice you tapping, especially if it wasn't fully locked in. And if you weren't in a sub, he probably didn't think you were tapping. After you train for awhile you get used to looking for the tap at certain points when applying a submission, so you generally let go instantly when you feel it. But if you're not in a position where another trained guy would normally tap, you're not looking for the tap so it's much harder to recognize when it comes. Especially if you're rolling with someone who's flailing around and 'tapping' you constantly with his hands just trying to figure out what to do. So make sure you're really assertive with your taps.