A Female Friend Had A Mirena In Fire A Free

A female friend had a Mirena in fire a free years now. She's not worried about getting pregnant. I finished in her on a Friday night. We had sex 2 more tines during that weekend. I didn't finish in her the other times but we took a plan b. We have been taking plan b after every time we've had sex. The other times we've had sex i didn't finish in her. She thinks it's an over kill and has confidence in that iud... should i be worried?