I'm unsure, maybe the flashback triggered a dissociative episode?
For me, certain flashbacks (as a kid) were triggered by panic of not knowing if I was doing the right thing right at that moment. This happened a lot if I was left alone for too long. If I wasn't getting constant feedback for being on the right track, I'd be left wondering 'am I being good?' Am I forgetting to do something? What comes next? I'd be too scared to ask; being unsure if I'd get in trouble for forgetting. I'd usually would be anyway because they'd say I wasn't paying attention. I was, but I couldn't hold it all in my mind while at the same time doing all the tasks set before me.
These worries happened, because I'd be in trouble frequently for forgetting multi-step instructions. I'd do the first part, but would forget everything after that, even when they'd go over it with me (but then leave the room).
I'd frequently do the front part of a worksheet/homework page, but forget to flip it over and do the back. I'd be so proud I'd finished -- then get insulted by the teacher (and my own brain) because I really hadn't finished. These things happened with non-trauma stuff, because of similar issues with associating similar trauma-related events. Not hugging my family tight enough, or sincere enough led to ... bad things ... to show me intamacy is important in family and it got out of hand and trickled into other things.
There was a snowball effect, and no matter how much I tried, my efforts were not good enough (because I didn't mean it ... that was a common complaint against me). I transfered my panic-triggers onto other things that were safer to deal with like school; effectively putting the trauma stuff out of my mind.
Forgetting or not hearing instructions because my focus was elsewhere, (inability to cast all my senses out into the world like fly fishing) is just a result of my natural introversion. I didn't know till I was an adult that I have to write things down before I can remember multi-step projects. My panicky reactions happen as a result of being unusually punished just for being myself. I didn't know I had to do extra stuff that other people didn't in order to remember things. To be fair, the adults in my life didn't know either. They just figured I wasn't paying attention, or I was just lazy.
Think of 2 hands and their fingers intertwined. My own natural issues on one hand (extreme natural introversion, lack of ability to express enough affection, punished for it, and making things worse), these fingers overlap my family's unhealthy reactions to my natural self -- inducing trauma represented by fingers on the other hand.