The play in question occurred with 3:35 remaining in the game, and with Kansas City in possession with a first-and-10 at its own 19-yard line.
Harris sacked Chiefs' quarterback Damon Huard for a three-yard loss, but pulled him down by the facemask, and was penalized 15 yards for a personal foul.
It is not known if Harris plans to appeal the fine, but replays of the incident indicated that the fourth-year veteran tackle did grab Huard's facemask. Huard was shaken on the play, but continued in the game.
The incident marred a monster performance by Harris, who is coming off a 2006 season in which he was limited to 12 games by a hamstring-related injury that required offseason surgery and a long rehabilitation. Harris had five tackles, two sacks and a quarterback pressure in the contest.
Len Pasquarelli is a senior NFL writer for ESPN.com.