I agree that the issue of you paying him, and the issue of Norma paying him, are two separate issues. If you were OK with paying him early, then that's entirely up to you. Equally, if you weren't, it would have been totally fine for you to ell him that unfortunately it's not possible.
If Norma doesn't pay him, he needs to address that with her. If you *want* I see no issue at all with you mentioning to George that you've seen Norma so it appears that she is not currently away, but you don't have to.
Edited to add: I would definitely *not* say anything to Norma. Her relationship with her gardener is none of your business, and you have to live with her as a neighbour - I think speaking to her has a huge risk of causing embarrassment, or anger, or at best putting you in the midle of her complaining about her finances and/or George's indiscretion, and you could find yourself manouevered into a position where you are expected to mediate between them. I wouldn't touch it with a barge-pole.