Yes, several people warned me of this transition phase. Frankly, I'm surprised it passed as quickly as it did.

Part of the reason, I suspect, was the several years training for very long walks. Three years of endurance training at nice low heart rates probably activated quite a bit of fat metabolism capability, meaning I was ready for the transition. Even though I'd still been eating a lot of carbs at the time, numerous walks in excess of 15 miles are surely going to produce some adaptation to fat burning.