Bulldogs World

My bulldog is almost 4 years old and for the past 3 nights has been leaking a very small amount of what looks like anal juice (but doesnt have that strong fishy smell) and little specks of actual poop over night. He seems to be doing this while he is sleeping and we have only noticed because it is on the bedding in the morning. Again, it is a pretty small amount, but is strange because he has never done this before. He poops 2-3 times during the day and his stools are solid and normal. He has been on Natural Balance Fish and Sweet Potato kibble forever and is on a strict diet for allergies. He gets some real baked sweet potato and fish as his treats. His skin/ears/nose fold has cleared up from being on the diet. I'm ust a bit worried about the "spotting" at night. I will take him to have his anal glands expressed, do you all think that is the issue? Although he has had full glands before and never done this. Any thoughts/advice would be much appreciated. Thanks!