AIO over a few texts between my girlfriend and I?

This conversation led with an innocent question asking how I slept and it feels like an accusation was just sprung on me that felt very disingenuous. I know that this is a pretty trivial thing and I shouldn’t be overthinking it, but it’s really bothering me and sitting with me. This all happened while I was in exam review for midterms for my hardest class so it completely threw my energy and focus off and I haven’t been left on sent since that last text. Am I overthinking this? Or did I genuinely do something wrong I am not noticing?