Some of them maybe a couple hours old when I upvoted. But they were still undiscovered yet (under $0.10) so it was still a good time to support. When you see a good post like those, you can expect the whales curators to come, welcome to #newsteem :)
This kind of things were unheard of before HF21. Undiscovered posts will remain undiscovered. No one bother to support them. It is different now.