Waking up at night after exercise

[Larissima]

After slowly increasing my movement in the last year to include walking 3-5 miles per day and 5 minutes of HIIT kettlebell swings 3 x week, I have now joined a gym. Yesterday I had my first session with a personal trainer, who put me through my paces mostly to see where I am fitness-wise: lots of squatting on different surfaces, a few sets on weight machines, some kickbox and core work to start and finish. I felt great, if exhausted, and had a restful evening with no dinner (IF - I had a small, protein rich lunch before the exercise session, though). Went to bed with 4.8 mmol/L, which is lower than I've been in the last few months, but not by much (usually 5+). Then, at about 1:30 am, I woke up and couldn't go back to sleep for at least an hour and a half. This is extremely unusual for me, so I thought it had something to do with my exercise session. I was not in pain, nor hot/cold, nor uncomfortable in any way, just couldn't fall back asleep and kept thinking about the gym and future sessions. I didn't think of checking my BG, but my FBG when I woke up in the morning was 5.0 mmol/L.

Any ideas if this was really due to exercise, or just the excitement? If it was some kind of hypo (though I felt fine), should I possibly have a bedtime snack after an intense session - though that would muck up my fasting? Please advise, as I love my sleep (and usually sleep really well).