Is this a Midlife Crisis?

Today the penultimate day as an employed man…

I’m (33M) unsure if this is an early “midlife crisis” or just a significant change, but I’ve launched my own business and going solo. I have everything all set, and work secured for the next year (and almost certainly the following 3 years too). Everything appears to be in order, but why do I still feel like the apprehensive 18 year old fresh out of school?

Has anyone else had this?