My girlfriend was taking loestrin and they switched her about two weeks ago to minastrin and she didn't realize you were suppose to chew them instead of just swallowing, will this affect anything?

Can effect the effectiveness. Should use 2nd form of birth control for first month at this point.
** also, I am sure you know that any of the pills are not 100 percent effective, so using a 2nd form is always a good idea