Lots of Err:ekf_check errors

Getting ERR: EKF_CHECK2 and 0. No change in flight, but I’ve seen others with the same issue eventually bite them lol. Can’t see anything in the logs. The only difference from all the other units is the autopilot is a Pixhawk 2.1. Here’s a really short log if anyone has the time:

2017-04-13 15-16-25.bin (2.5 MB)