Mangrove Jack's M42 Apparent Attenuation

I brewed 5 gallons of a basic 6 row pale ale as my first homebrew 5 days ago. I mashed for 60 minutes at 149F, my OG was 1.043, and I pitched 1 sachet of M42 at approximately 70F while waiting for the wort to reach my setpoint of 67F. Approximately 72 hours post-pitch, I bumped my setpoint up to 72F since the airlock activity appeared to be slowing.

As I post this, I'm approximately 120 hours post pitch and my hydrometer reading shows 1.004 when adjusted for temperature. When compared to the OG, that has me at 90% apparent attenuation. The manufacturers literature shows the expected attenuation for M42 to be 77-82%.

Has anyone experienced this yeast attenuating at this rate or should I consider less favorable possibilities for what is occurring in my fermenter?