Advice on changing a character's name?

The current story I'm working on has a crew working on a ship (independent, non-military). At one point, they meet a military general who wants to defect. Initially, the narration only calls him 'the general' until he tells the main character his last name, then he's referred to that way. Then about half a chapter later, mid-defection, we learn his first name.

I *think* I've dealt with it well enough, but I can't help but feel a little cautious that I've changed a character's name 3 times. Is that breaking a rule of some sort? If the character is likable enough, the reader is invested enough in the story, and the scenes regarding his name are clear enough, will it be confusing for anyone?

I've considered the reverse... you learn a characters name, then learn nicknames or ranks later, and it doesn't cause any issues. Maybe I'm making something out of nothing. I just want to get some reassurance so I don't have to keep worrying about going back to fix it (assuming it isn't a problem).