I've been seeing BF for a few months, everything is going really well. I feel our relationship is pretty equal in terms of paying for drinks / dinners / nights out /take aways. I am mindful of money and actively avoid ordering pricey things on the menu if I think he might be paying. I will often bring things over to his and he will do the same when he comes to my house. I'm quite generous and don't ask for money back for things, for example, he will ask me if I mind getting supplies from the shop for him and I will happily buy them and when he asks how much it is I will tell him not to worry. He will also get things in for when I come over that he knows I like or bring bottles of wine to mine.
There are two occasions that have slightly irritated me and both revolve around being 'treated' and then asked to pay half in the following days. On both occasions we have been out for dinner, he has paid at the time (with no discussion of paying half), I say 'thank you for treating me', then I'll get the next one or I'll make sure I make up for it in other ways like buying things for his place. Both times he has then text me the following day asking if I'd mind paying some money towards the dinner. On the first occasion I just sent the money across no problem, but this time I was a little annoyed to be honest... so I asked 'Why didn't you ask me to share at the time?' He then replied saying he'd only thought about it today after having a look at his finances. There have been times where I have retrospectively realised I shouldn't have paid for things as it impacts me (like buying shopping for his house), but I would never dream of asking for the money back in the following days. 
AIBU to be a bit annoyed?