Almost every time I fly I get a compass error. Re calibrated compass and IMU numerous times. Compass failure and atti mode at least 50% of flights.

Should I send it in for warranty?

"You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged."

Also, you should check how that bar goes if you move gimbal up/down. Let us know

Axeli Posted at 2018-5-27 10:35
"You can view the current compass interference in the "Main Controller Settings" --> "Advanced Settings" --> "Sensors" section of DJI GO. The colored bars should be in the green (Excellent) range when the Mavic is in a location that is away from magnetic influences. If the bars are in the red (Poor) range or close to it, move the Mavic to a different location and check again. If the compass interference is still in the red (Poor) range or close to it, the compass could need calibrated or it could be magnetized/damaged."

Also, you should check how that bar goes if you move gimbal up/down. Let us know

I always check the compass and IMU prior to flight.  Everything was green.  

That's really weird then. I would send it in.

Don't risk a crash or loss of your bird. Just send it in. Better safe than sorry.