Hat Trick Achievement Glitch?

I was poking around a clearing in the moss blanket, trying to get up onto the trees and such to take a good look around, when for no apparent reason, as I jump onto the tree's canopy, the Hat Trick achievement unlocked. I've only seen two gold slimes in my 31 hours of play time, and have yet to even successfully feed one...I've no idea if it was a weird hiccup in the game or if it's a legitimate glitch, but it may be worth exploring?

The clearing I was in is the one that the log slide leads into with a pond in the middle of it. I jumped onto the leaves that overhang the pond area.