Is it normal for my voice to go back up in pitch after deepening?

Your voice will not go up in pitch, but it has developed more range because you have matured. As you get more used to your new voice, you can learn to have better control over how you use it. If you are a singer, the time of day that you choose to sing has a lot to do with the quality of your sound. A lot of professional singers feel that they cannot sing well in the morning and will refuse to perform then. If you are a singer who practices then you may have developed a broader range.