Ziggs W tooltip bug

When I looked at the tooltip for Ziggs' W Satchel Charge it showed the base damage at rank 1 was 70. After using the ability and while the satchel charge was still out the tooltip read that the base damage was 60 instead. After the satchel charge explodes and the ability goes on cooldown the tooltip once again says that the base damage for the ability is 70. The damage from AP scaling did not change. At all ranks of Ziggs' W the tooltip would display a slightly lower base damage while the ability was out but not detonated yet. I know this is a small bug but I thought I would just point it out.