A Word Problem

I saw this in the 7/8/2007 "Ask Marilyn" column of Parade Magazine:

Kevin's wife picks him up after work every day at 5:30 pm.

One day, he leaves at 4:58 pm and starts walking home.

She picks him up along the way, and when they get home, he notices that they saved 4 minutes.

How long did Kevin walk?

Please click here for the answer.