My boyfriend (M23) drove my car tipsy, hit a curb with me (F21) in the passenger seat and put half the blame on me by saying I had to have known he was drunk

We share my car, so the entitlement is quite high right now. This incident occurred a month or two ago, however the conversation regarding the blame was brought up the other day. He had basically joked about the whole thing saying he was tipsy enough to have had gotten a DUI if we hypothetically got pulled over, and I was completely shocked and told him I wasn’t aware he was tipsy. He said “you had to have known. I drank a few hours before we left. You knew I was driving drunk so half of it is on you.” I was completely taken back by the sudden blame and told him I had absolutely no idea he was still feeling the alcohol after so many hours and that it’s ridiculous to blame me for it. I told him I had explicitly asked him how he was feeling before we left the apartment and he reassured me he was fine, therefore we went. He continued to go on about how obvious it was and that “I totally knew.” I felt uncomfortable and shocked about this confession of his and the conversation faded but as I think about it again, I’m feeling quite angry by it all. I plan on approaching him about this again soon, telling him how the conversation made me feel.

As a partner, otherwise, he’s completely loving and compassionate for me in every way. He looks at me like I’m his other half. This is just totally out of his character. Should I take this as a red flag or a one time mistake?

We’ve been together 4 years, living together for 1 year.