Oil changed 2800 miles ago, everything was fine no beepers and FSS showing 4200 miles until change of oil needed service A.

HOWEVER-

Today while driving, a warning beeper came on and the oil ICON showed HI.

After 1/2 mile the beeper and icon went off.

Approx 3 miles when it was safe I pulled over and manually checked the oil level, it was fine. I checked the FSS it still indicated HI.

I drove back to my office and rechecked the FSS and now it shows 4200 miles until the oil change is needed and service A, without showing HI.

Any ideas?

Thanks