If you succeed and you didn’t predict it, it isn’t success, it’s luck.
Luck is fickle. It comes, it goes, it gives, it takes. You can never count on luck.
Being successful without without knowing why, without being able to replicate it and build upon it, isn’t success, it’s a failure.
Be thankful for it. But don’t celebrate it. Get back to work and figure out how to have predictable success.