Correct, he posted the pictures retrospectively. As did Jesse on Facebook, posting pictures a few days ago of them at the Pink concert in Sydney a few weeks ago.
You’re looking into it to much, the pictures were not posted while he was there.
I know Luke personally, and I recall him posting a number of stories a few weeks back of being in Canada.
Being a flight attendant, he is regularly popping up in places and then posting pictures about it later.