Well, I went and took a look at my training journal (excel spreadsheet). I generally just note what I did and how I was feeling, in addition to the standard date/time/duration of ride.
Two of the last three morning rides have left me feeling like this; one of them ended in a full-blown bonk only two hours into a three hour ride. So bad that I had to get off my bike for 30min, eat a LOT of convenience store food, and still barely made it home.
So, I'm thinking there is something to this. Maybe I'm not eating the right things before morning races/rides, maybe I'm not eating enough, maybe I'm not sleeping enough (only got 6hrs of sleep Saturday night, but I've been fine on less before), etc.
And, really, this race was probably one of the easiest races I've done this year...Cat2-only crit. Before the race I felt/knew that I was capable of rolling with any move that went up the road. Felt like a top-5 result was definitely possible.
Something in my pre-race preparation just flat out failed me Sunday. I'm not happy about what happened, and I'm going to do more morning rides on the weekends this fall/winter to see if I can diagnose the problem and prevent this from happening in the future.