Garlic disease?

Hello.

I've just bought some seed Garlic from a garden centre, Thermidrome variety. Upon opening the bulbs and breaking down to the cloves prior to planting, I discovered what looks like insect damage. It was in the soft flesh hidden by the usual white papery covering that garlic produces. I want to know if it's just bruising from poor handling, or some disease the garlic came with, and I should be burning everything they've come into contact with.