That’s true. The only protocol I know of when a foreign leader meets the Queen, is that when it comes to shaking hands, she has to initiate the handshake.
I may be mistaken on this but I seem to recall that when a man and a woman are introduced the man doesn’t extend his hand for a shake unless the woman extends hers first. It would make even more sense with a man meeting an older woman.
Still, it looks like the greetings went just fine.
Peach