The hell? Email Fang or whoever and get correct-sized pads. I hear/read he's just sending people the fabric for the pads for them to replace themselves after some of them started fraying to avoid having to ship the HE5s back and forth so maybe he'll send you a whole pad too. Or maybe you can figure a way to remove the fabric, trim down the more padded side and put the fabric back on. Either case, QC fail and I wouldn't doubt that there are huge variances in sound among HE5s. I think the pads can be taken off, but haven't read through the thread on HF thoroughly enough to tell you right now.
Edit: Oh, maybe he's just sending whole pads. My bad, that makes more sense.