When you remove the drain plug there is a magnet on the end of it which will be filled with filings. I've seen some guys on youtube show you how to flush the tranny, but on my 97 Civic and 94 Accord I never went that far. Just do a few drain and fills with the next two oil changes (3K to 5K apart) and you will be ok.
You may need to replace the crush washer that is on the drain plug. It is removed with a 3/8 inch rachet head.