It's logged as a disk problem, but the sectors were successfully re-written, hence the disk remaining enable, good idea to run a SMART extended test, and if it passes monitor this attribute, you can add it to the SMART attributes monitored by Unraid for any WD disk, if it continues to increase there will likely be more errors soon:
ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE
1 Raw_Read_Error_Rate POSR-K 200 200 051 - 35