SMITE BUG

Hi recently I played a game as Lee Sin and i ended up getting 2 kills off of an invade early in the game. I backed and bought the upgraded smite and I Immediately had 2 full stacks of smite. I thought it was a visual bug (it was before 1:55) but then i went to red and was able to smite that and again in 15 seconds. I don't know if this is intentional!