Ezekiel scoffed at Oolong, he didn't forget the yggdrasil leaves, he simply didn't care to bring them on their last job together, which he forgot exactly when that was. There weren't too many people he could care much for keeping around long.
"Well I really don't feel like sticking around Prontera much longer, too many people making too much noise and too much stench. I'll just meet you all in Izlude, I can gather supplies I need well enough there and think a lot easier. Oh and Oolong...I won't "forget" anything this time." He then goes over to the kafra and deals over some zeny to get away from them at least for a short while in Izlude.