Now is OK, means working fine?
If this the case, he solved the problem, just the piston jam, after lube and service, piston smooth out... enjoy the ride.
one more reason to you cause might be bad venting, when heat up, brake fluid expanded and without proper venting, it jam the brake.
Please clean you reservoir cap/cover...both front and rear regularly.
The venting is very important.
Hope it helps
I am not so sure about ABS...