Yes, spinach. But it is supposed to only last 7 seconds. I have had the Impervious Miner too, at the same time, so at least we know not all buffs cancel the High Jumper.
Another two hours later, my connection crapped out and when I logged back in, the High Jumper Buff was gone. I wonder if this extended benefit is intentional or just a... well, you know, a glitch. Either way, it was fun. :)
I loved it! Felt like flying, especially when triple jumping. xD
I was visiting the Dragon in Unnu Slight when it happened, so I guess it was his fault...