Ex is coming to pick the kids up today and conversation follows..
Me: Can you please buy some sugar for me when you come to pick the kids up today? I don’t have any cash on me, and you know the corner shop want you to spend at least £5 before you can pay with card.
Him: It’s not for my kids, then I’m not going to buy it.
Me: If you asked me to buy milk/sugar on the way to your house. I would do it, it has nothing to do with being in a relationship It’s a small favour people do for each other.
Him: When I take the kids get up off your arse and walk to Tesco. (Tesco is 10 min from me)
Really? 
AIBU to think this is just a small favour people do for each other? It means nothing?
Some days we get on, and there’s days like this where I just think what the fuck just happened? I thought we were fine before this. We split up 2 years ago, got back together again and split up again January this year, because the same issues were still there. I think he’s just bitter and coming from a place of hurt, even though he’s in a new relationship. But he was fine with me a week ago so confusing.