No worry - that happens to me during the day. All the time.
Left drift is normal for a clockwise turning heli due to tail rotor side blow countering rotor torque. There's a param called ATC_HOVR_ROL_TRM which is set to 300 centidegrees by default. I forgot to mention that before. What I do is put the heli on a level surface of some sort, set that param to zero, and then use my digital pitch gauge for setting blades to level up the heli on the table so the mainshaft is perfectly vertical. Then I adjust the AHRS trims until it shows zeo pitch and roll in the ground station.
Then take it out and fly it with no wind just in Stabilize and make it hover perfectly stationary for about a minute. And while you're doing that you can observe the right-side tilt of the heli frame required to hold it there. Then pull the logs out of it and look to see what the actual degress of correction there was that was required to hover the heli in one spot. Adjust the AHRS pitch trim to match that, and add in the amount of ATC_HOVR_ROL_TRM in centidegrees required to hold it. Then fly it again and fine tune it with the AHRS trim.
I don't know if that's the right way to do it. But it's the way I've always done it, and always ended up with good results. I typically end up at somewhere between 300-400 for the ATC_HOVR_ROL_TRM. But on my nitro 700, which carries a Sony camera on the right gear leg, hanging off the side of the heli so the weight is not balanced, it was only 220.
Here's a photo of how I do that. You'll notice the paint mixing sticks under the landing gear to shim it up until the digital pitch gauge shows the heli is level and mainshaft perfectly vertical. And then I adjust the AHRS trims to get zero pitch and roll shown in APM Planner2.