No it's not normal. These gray stools usually tell you that there is not enough bile and that you may be badly constipated.

May also be caused by parasites, particularly if you have gas.

They can also indicated that you have an infection in the liver or that the pancreas is non performing correctly.

Have you considered having a blood test to rule out possible serious causes. You could then consider trying to decongest and clean you digestive system by using the protocols found on curezone.