Oh yes, that´s true. But it depends on wether you are in a club. 72% age graded means to pass the test for a club runner with some ambitions, but not more. Sub 18 for a masters runner and in my club the people start to take notice.
By the way, beyond the 40, the pure training volume will become less important and the quality will be top priority. And 30-35 mpw is not bad for a masters runner aiming for a 5k. Maybe OP will run faster on more mileage but there is no guarantee for that.