This is similar to my experience (mid 30s now). I remember sitting at my desk at work, staring out of the window, thinking "wow..so this is it". Would've been about 28-29. I think a combination of things got me to that headspace: end of the education-career pipeline, having bought and settled into a house, and having no kids. I reached a point where I was no longer occupied with achieving "my" goals, and I was left to figure out what my life was going to be. I guess suddenly becoming aware of that responsibility isn't very pleasant; before, I was just on the rails society lays out. School, job, marriage, house, kids, career, etc. Easy.
I'm not much interested in the pedantic debate taking place elsewhere in here about what truly qualifies as an x-life crisis. To me, it's a point in your life where there's some anxiety associated with the direction of your life. I'm more interested in how people came to think about their lives in and after those moments.
Roger Waters of Pink Floyd was 28-29 when “he realised he was no longer preparing for anything in life, but was right in the middle of it” and was inspired to write the song Time for Dark Side of the Moon (the reader is encouraged to listen to it now). Each individual responds to this realization in their own way.
"No one told you when to run, you missed the starting gun."
Tame Impala's Currents is an album written around the same age with a similar theme in mind, and fittingly part of the new guard of psych rock/psychedelia.
I'm sorry to say I don't think it's struck yet! Not to say what you experienced wasn't real by any means, but I think it just sounds more like a different, but normal thing. The coming to terms with reality after your 20s. I think you'll see another round more characteristic of the mid-life crisis as you all enter your 50s.
Most are doing well now as we hit 40, curios if is struck sooner for our generation.