Hi Hana.
Possibly the effects of a liver dump perhaps ?
You had only chicken which is no carbs, then some strenuous exercise, then a brisk lengthy walk. You say yourself that you felt tired, possibly because your Bg level dropped too low because of all the activity and no carbs, so a liver dump pushed your levels up higher to compensate. Do you ever check your Bg levels before and after exercise ? My thoughts anyway ?
As LR says, for me pretty normal really. Nothing I would be concerned about.