[mrlmd1]

If you're going straight ahead with the steering straight you don't have to worry as much as you did, but for the first time, that's expected. And sometimes going VERY slow is actually harder and more dangerous than just a little bit faster as the bike is more stable at a little speed because of the gyroscopic effects of the spinning wheels and is easier to balance. Just loosen up, let the bike do it's thing, don't hang on with a death grip and overcompensate for every little wiggle in the road.
Glad you made it. Now try it on a turn.
Just remember going slow around a sharp or tight turn - DO NOT apply the front brake or you will go down. Part of the cause may be the slippery road with gravel, sand, or anything else you want to blame, the rest, and the main reason, is the geometry of the steering and the laws of physics (or, in other words - operator error).
And you're going ATGATT right? Just think what all that sand. gravel. hot asphalt would have done to your skin.