I confess, the first brew i did that wasn't Mr. Beer was an extract kit with steeping grains. Not knowing anything about brewing yet, and before reading every book, i left steeping grains in for the entire boil. Truth be told, i didn't notice anything horrible about the beer. It was a Trappist style beer with a ton of dark and crystal malts. I didn't detect much astringency, however i was very forgiving for my first 5gal batch.
If you already did it, there's no turning back. Follow it through and don't get too worried about it.