YMMV. If the check in is at a station managed by Cathay staff and not outsourced staff they may look the other way. I have certainly had this experience before both as a GO and DM.

But in life there are no guarantees and there is no stated policy governing this so don't I wouldn't go there with an expectation of entitlement. Be prepared to pay the overweight fee and then be happy if they just overlook the issue entirely and send you on your way without any comment.