Tahm Kench Thinks Turrets Taste Gross

Just had a game as Tahm against a Heimerdinger. I noticed two things: 1) sometimes after eating a turret created by the Heimer, TK would immediately drop it or keep it for a little and fail to spit it out (putting his ability on cooldown, not sure as to whether the damage occurred); Tahm would occasionally make turrets he ate invincible.