An example of a horizontal side-moving door with a side-winding or horizontally translating curtain includes an upper seal comprising an upper edge of the curtain sliding within a groove of a seal guide. To protect the door in the event of an impact, at least a portion of the curtain's upper edge can restorably pull out from within the groove. To avoid damage in certain situations, the seal guide might resiliently deflect as well. After an impact, the curtain's upper edge is automatically fed back into the groove by simply opening and closing the door. During normal operation, the curtain's upper edge advantageously deflects in response to air pressure against either side of the door. In some examples, the seal guide is of a uniform cross-section, which makes the seal guide easy to manufacture by way of a conventional plastic extrusion process.