What do you think about my MILs comment?

So it was my SO’s birthday on Friday. My SO requested I make him steak, veggies, mashed potatoes (it’s his favorite dinner that I make lol) so I bought the stuff the day before. And my son spends the night every Friday at my moms, so we were gonna have a nice little date night. But, my MIL called him & asked what hes doing for his birthday. He told her what we were doing & said, “oh well how about I take you out for a nice dinner?” He told her that he’ll get back to her, that he’s gonna ask me since we had a dinner planned. When he asked me I was like sure that sounds nice I don’t have to cook lol. So then he calls her back & says “She said she’s down to go. What time should we be ready? And Ricky (our son) will be at Selena’s (me) moms.” She said “oh I thought it was just going to be me and you. But if it’s not going to be then bring Ricky I want to see him.” So he was like ok then hung up. I told my mom we’d be dropping my son off a little later. So we end up going to the restaurant & had a good time. Then the check comes. My SO takes out his wallet my MIL says “ oh I’m paying for you! I asked to take you out” & he says “oh foreal thanks mom” & starts to put his wallet away. Then she sees & says, “well I’m just paying for you & the baby. I asked to take YOU out & to bring ricky .”She says it in a serious sort of tone. Now I didn’t even expect her to pay for any of us, even my SO. So We didn’t mind paying. I just thought it was weird how she singled me out like that, & kind of made it seem like she didn’t want me there. I just want to know what you guys would have thought. We’ve been together for 5 years now by the way. My mil and I never had an argument before, but she has made some snarky comments towards me about things I should do for my SO.. she’s very traditional. For example, she seen him serve me dinner one time at a party & pulled me aside to say that I should be serving him. What do you guys think? Oh and my SO just ended up paying for the 3 of us.