It's the BPA in the can linings
(and before anyone goes nuts, that's a joke. Well, sorta)
Given that this is an IPA, I actually was wondering about that (not the BPA specifically, though). Do hop oils adsorb to can liners, and would it happen to the extent where it would have a noticible impact on flavor? (I'm a canning noob, so I am asking this as much for my own insight as positing a possible mechanism for the OP's original question)