What could this mean?

My (m28) wife F(25) and I have been married for 4 years and have 2 kids so we are in the weird stage where we have sex once a week due to exhaustion from babies. We are deciding if I get a vasectomy or go for 3 or what which makes the bedroom a bit weird. Our marriage hasn't been the most healthy thing ever. We met and got married regrettably quickly and have some major differences but I think we do try in our own ways for it to work. We talk openly about this and have talked about what life would be like separating or staying together. We are both working very hard to pay off debt and get somewhere with our lives which has brought us closer id say. Im just setting the stage here.

Tonight we had sex for the first time in a week per usual. Everything was normal. We do what it takes for her to finish first and then I follow up. It's been this way for 4 years. We are both satisfied and enjoy it. Tonight afterwards she asks if I want to go again so she can finish again like usual. I give her a weird look like when have we ever done that besides the first weeks we met 4 years ago. We acted like this is something we do daily and got pretty defensive when I pressed on it for a second. Is she projecting what she wants to happen or is there something else going on? Is she confusing someone else. She got very defensive and kinda shifted it to me being the asshole for asking. I did ask genuinely what she meant by it only for me to be shut down.