[GAMEPLAY] Sated+Gift of Heavy Hands doubling turrent damage proc?

Not 100% sure this was a bug, but felt super wrong to me. I was , Item build- Runes- 15% Attack Speed, 13 Armor, 3% Lifesteal, 7.5% cdr Masteries- 9/21/0, Buffs- Gift of Heavy Hands (jungle buff for smiting Krug), Baron buff, 2nd dragon and Level 18, around 38mins into game.

Final push mid, ran up and Q-hit middle inhibitor tower (did not use active if that matters), was expecting to maybe chunk 1/5th of it's health. Instead, I took maybe 3/5ths of its health..in 1 hit. Now I know I was sated, q charged, krug buffed, but it still seemed insanely high for a single hit. Especially considering I was mostly tank/attack speed, no damage build. My followup attacks did barely any damage to it, think I even got a 2nd Q hit on it and didn't seem notable damage.

leagueoflegends.wikia says krug buff on towers does- (65 + 15 x level), or 335 true damage at level 18. I have a feeling somewhere between sated and Shyvana's q, it doubled or maybe tripled that? As far as I know, even with double tap AA's, you should still only be doing 1 proc of krug buff, as it removes the buff on hitting the tower.

Unsure of reproduction rate, only seen it once. Steps to reproduce- Play Shyvana, get devourer, get 30 stacks, smite krug and AA a tower with Q charged, check damage output vs the 65 + 15 x level bonus it should be doing. Sort of difficult/time consuming to reproduce, sorry.