No. You can make yourself one with velcro if you have half an hour. IKEA mattresses come rolled up and the handle/wrap piece can be asily adapted to make a handle.
BUT the frame has a couple of comfy hand hold points and the new saddle with the finger grips is OK for short carrying.
To be honest, carrying a Brompton too far isn't that much fun however you do it, better to raise the seatpost and wheel it (rack helps here) or unfold and push wherever it isn't possible to be riding - along a station platform etc.