I don’t see anything out of the ordinary in the menu builder. For testing, I added a new page to the top of the menu (Terms of Service) and the issue remains.
The only thing I can think of that I’m doing out of the ordinary with my menu is using an icon plugin: Menu Icons. However, there isn’t an icon on the first menu item where the issue is.
I’m pretty sure it was centered yesterday. Today I spent some time updating my logos and tweaking the header padding. (not sure if that info is helpful to you).