He may have felt insecure and fearing rejections hence, telling you about his age later in the relationship.
If he had in deed shared his age, it shows that he at least trust you and is hopeful that you won't hold the age difference or his earlier silence (about his age) against him.
It all depends on what you want to get out of the relationship. If you are in love and want to have a future or if you just want to explore the relationship but w/o any strings attached.
You do not have to make any major decisions right away. Go with the flow and see what else comes out of it.