If you have had a change of medication, or a change of health (like diagnosis of pneumonia, or thyroid disease), you might see a change of numbers due to those circumstances, and not because of simple progression of the disease. When I was diagnosed with Hypothyroidism, and went on synthroid, I saw an increase in my fasting, and other numbers. I did some research, and this was normal.
I also see an increase every year in both fasting, and post meal numbers during my worst allergy season. They can be 20-30 points higher at times!! I tend to cut back on carbs, go back to my South Beach stand-bys, and wait it out until all the blossoms are off the trees.
Since you have been a diabetic for a long time, I can assume it is not allergies. But, look to see if there have been any changes that might be the smoking gun. If not, I would take your log and discuss this with your physician. It might be a progression of the disease.
The fact that you are concerned, and paying attention to this is great. It means you are going to nip it before it gets worse. Taking action now can help make things better in the future.