it sounds more like hyper-vigilance to me, which makes sense as a ptsd symptom, and for your particular situation in that respect. Being in the lockdown without knowing where the threat was coming from meant it could come from any direction. It sounds like the incident in the grass reflected that feeling: not knowing where the danger could come from.
I know when my hyper-vigilance kicks in (lately it's only under triggered conditions and under a lot of stress), I startle at every noise and scan for any signs of potential anger/violence. I interpret signs of anger where there are none simply because it helped me survive through my childhood. It can be very intense, and sometimes I have it mixed in with milder flashbacks, which just makes everything really confusing. I also know sometimes my flashbacks get jumbled. By that I mean I re-experience more than one situation at a time. The events merge and get tangled up in each other so the flashback ends up sounding more like a hallucination to someone else, but they are a bunch of parts of several situations that all actually happened, just not all at the same time. So in that sense, they are not flashbacks in the traditional sense.