Is my new Time Machine backup okay if my MacBook went to sleep during encryption? I started a new Time Machine backup last night and enabled the third-party app Amphetamine to keep my machine awake for 9 hours. When I returned in the morning, it appeared that my MacBook went to sleep after those 9 hours, but Time Machine still read "Encrypting...".

Is my Time Machine okay, or do I need to wipe it and start again?

After this, I ejected the Time Machine drive and plugged the it back into my Macbook when I got to work. It backed up a new 500 MB of files and went back to encrypting. This makes me think that perhaps Time Machine dealt with the MacBook going to sleep fine, but I want to make sure.
Your Time Machine backup is OK! 

The encryption process is completely resumable, and it does so automatically.