Yes, it is very normal. The most common cause of these symptoms is the mucoid plaque. When plant foods begin to interact with the mucoid plaque and break it down you can experience temporary healing responses where micro-organisms act on these broken-down substances producing toxins and gases. This is why regular colonics / enemas are so important for accelerated healing.
It is also normal to experience these symptoms as the lining of the intestines is healing and being rebuilt. In this case herbs and supplements can assist in the healing process so as to reduce or eliminate these side effects. Lightly massaging the abdomen and intestines can assist in accelerating the elimination and healing process.