First there were six, than there were five.
P40 was dated by Aland as coming from the third century. As far as I can tell from the few letters I can see clearly in the pictures (here), this is very optimistic indeed. I am glad that the holding institution agrees and suggests a fifth/sixth century date. I suggest we adjust our lists to reflect this uncertainty: the first couple of decades people still know that Aland's dating is disputed, afterwards we state it as fact that the papyrus comes from the third (the usual shift from opinion to certainty). That still leaves five witnesses of Romans dated to the third century (P27, P46, P113, P118, and 0220).