Exactly, he said it as a question, not a statement, and he said it pretty mockingly. It pretty well disarmed the villain’s tactic of trying to intimidate Bond through some homosexual molestation, so I’d say it was simply a cheeky remark on Bond’s part, not some gay confession.
Not to mention, Craig’s character is the most hetero Bond since Connery, so reading it the other way doesn’t make much sense in context.
Cheeky? Are you watching muh bumb?
Well! Are you?
You are!
Aren’t you?
You bumb watcher!!!!