You may have expected that enlightenment would come like zap! Instantaneous and permanent. This is unlikely. After the first "aha" experience, it can be thought of as the thinning of a layer of clouds.
Who cares if you're enlightened forever? Can you just get it in this moment, now?
Enlightenment is not an attainment; it is a realization. When you wake up, everything changes and nothing changes. If a blind man realizes that he can see, has the world changed?
A person who says, "I'm enlightened," probably isn't.
No man remains quite what he was when he recognizes himself.