Hi. Not sure if I'm being the unreasonable one here, but I'm sure you'll tell me if I am 
Ex husband/father of my children has the kids every second weekend. I always pack them a bag, and they bring the dirty clothes back home at the end. Fine.
So he had them this weekend, and dropped them off tonight. Prior to the weekend, I had asked him not to send them back with the dirty laundry, and politely requested that he do it at his (for once). Reason being that he will have more spare time than me over the holiday, as I have the children for most of the holiday, and it will be full-on. Plus we are going away for a couple of days from Christmas Day, and I didn't really want to deal with a load of dirty washing. Also, the kids' presents are done at mine, and the house will be a total riot anyway!
He had messaged me back to say that this was a bizarre request, that he had never had to do their washing on previous weekends, and wasn't about to start. I very calmly replied that this was fine, but that he should buy them clothes for his place, as I wouldn't be packing any more bags or doing their laundry from his time with them.
Kids arrived back a few hours ago with, unsurprisingly, their unwashed clothing from the weekend.
Am I being petty? Is he a 1950s arse? And how do you and your ex manage this situation?
It is Christmas Eve, so any kind and supportive replies would be much appreciated (although I don't mind being respectfully told if I'm in the wrong!).
Many thanks.