Yeah, Worf changed his hair too from his traidmark braid.
Honestly sometimes I think the Klingons just see Worf as "the Starfleet Klingon" and don't look past the uniform so often.
Changeling-Martok recognizing Sisko, while not impossible, did surprise me. Honestly I'd have thought Gowron would have been the one to do so, having looked directly into Sisko's eyes. Good thing Worf's alias wasn't called up there. Gowron definitely would recognize him! :P