IAD-FRA has significant walk-up (maybe not quite, but last minute) who purchased refundable/changeable fares in F/C or whose corporate contract allows refund/change. Not uncommon for team of 4-6 headed to a meeting who cancel / change at last minute. That can turn an inventory of 0 into 4-6 in appropriate bucket in a second. Unless you have another use for the CR1, why shift it?