From my own experience playing on a low-pop server with only a dozen or so serious pet collectors I'd say that it is quite normal that you will encounter a wild mix of battle pets and not just the new ones on the Broken Isles. This might be really nice for people who want to catch up on collecting, but quite annoying for the rest of us.
In your specific case regarding the Spring Strider
you probably just had a lot of competition from people who were on the Wildlife Conservationist
world quest yesterday. I noticed that the required pets can become rather rare during times of this and similar world quests.