Like, one extra loop total, or an extra loop for every stitch? If the latter, you may not be pulling the index finger yarn THROUGH the thumb loop. Are you accidently catching the thumb loop in the process with the needle? You should be going through the loop completely, and not catching it with the needle, so that the thumb loop yarn closes around the other yarn, but not around the needle. If that makes any sense....
KnittingHelp Queen Bee
"There is a vitality, a life force, an energy, a quickening that is translated through you into action, and because there is only one of you in all of time, this expression is unique. And if you block it, it will never exist through any other medium and it will be lost. The world will not have it. It is not your business to determine how good it is nor how valuable nor how it compares with other expressions. It is your business to keep it yours clearly and directly, to keep the channel open. You do not even have to believe in yourself or your work. You have to keep yourself open and aware to the urges that motivate you. Keep the channel open."
— Martha Graham