Likewise I hit a 8.8 yesterday at 4pm after eating a very small lunch at 1pm, I went for a 2hr walk at 2pm, after checking my BG post 1hr meal was 6.2 towards the last 30mins of walking I felt a bit hypo weak legs etc, when I got in at 4pm BG was at 8.8 so I assume my liver thought I needed a boost and dumped on me, so given how I felt on the walk, I'm thinking a (false) hypo, I fasted the rest of the day, now this morning BG is 6.0.
I find this happens every now and then, bit of a pain in the rear but at least it settles does down.