Check out the info under #3 in the following link if you haven't already.
Troubleshooting Information | EBC Brakes
This is the part that stood out to me;
The video at this link shows how to correct for brake vibration caused by DTV (Disc thickness variation). DTV develops in a car after 3000-4000 miles caused by runout built in to the car or due to incorrect alignment of the rotors at install. This is quite a common fault on modern cars and many cars require this at every rotor change. Drivers also confuse hub distortion with a rotor quality issue but in 99% of cases the DTV is a car problem, not a rotor quality problem. You can replace the rotors as many times as you like trying to solve vibration and the problem will only go away for a few thousand miles and then return. This means you have purchased new rotors in good faith but the problem IS NOT SOLVED AND WILL NOT GO AWAY PERMANENTLY until you perform this procedure. After this skimming of the rotor surface you will have smooth brakes , more effective brakes and ZERO vibration. It is even a very worthwhile practice when fitting new rotors to have all four rotors skimmed into perfect alignment on your car with this inexpensive procedure.
According to the link, it seems that most of these issues creep up after around 3,000 to 4,000 miles, which sounds similar to your issue.
I also doubt your driving style is causing the issue. You could always have the rotors turned, make sure the hub is squeaky clean and then re-bed the pads.