Low diastolic blood pressure

I recently have been noticing a Low diastolic blood pressure, I am 32? I am a 31 year old male. In excellent shape, 170 lbs 5 11 - I have unexplained hypertention. I have been on 40mgs of accupril for most of 9 years. I recently went to a cardiologist for an annual check up and received a echo and stress test, check for LVH and other cardiac issues. All results were normal. My blood pressure usually reads 125/80 w/ medication but recently I have been seeing lower diastolic pressures 125/65. My doctor added a diuretic to my treatment last year and I have stoped weight lifting which my cardiologist suggested might not be good for a hypertensive. Since then I have been running on average 8- 10 miles a week. Like i said my last cardio echo was perfect,.....could all this cardio and running be lowering my diastolic? If not what could it be if my echo s are clean ?