Hello Alì,
have a look at the following field notice that describe problems on some linecards this could apply to your case.
http://www.cisco.com/en/US/ts/fn/610/fn61776.html
Edit:
actually it doesn't apply to you. However, only one port has failed the test.
in a maintanance window perform module reset with
hw-module slot 8 reset
check if the error appears again.
Hope to help
Giuseppe
