I think they both do it, but it is more bothersome on the MT. I only notice it on the 3-4 shift on the freeway; sometimes I think I am pretty much up to speed and I let up on the acclerator and it lags a bit before 4th catches. I've pretty much gotten used to it, and yeah, it's normal. Emissions are reduced somehow by not allowing the throttle to immediately drop.
Anyway, this mod is already all the rage over at
ElantraXD.com!