Glomerular filtration rate is 42; last january was 40. Dr. Never mentioned it. Is this common at my age? Should I see a urologist immediately?

Low GFR. You should see a nephrologist. You are 67 years old and have anemia, you could be anemic from chronic kidney disease. You have a 42 ml/min egfr, the "e" is for "estimated". You need to get a 24 hour urine collection (u) to see what you actual GFR is. See a nephrologist (n) for the u, have blood drawn and get an ultrasound of your kidneys done. If you have an obstruction, he n will refer to a gu.
A good idea,,, It would be a good idea to see a urologist or nephrologist soon as your GFR is low and they can look at your kidney function and readings as a whole. Poor kidney function might also be a reason for your anemia as the kidneys make erythropoietin which is important to help the body produce red blood cells. Best of luck.