No that doesn't sound like an issue. He was all the way out before it came off and precum is only an issue if he didn't have a condom on at all.

Plan B doesn’t “mess with your body”. It’s changes your cycle to help prevent pregnancy. Of course, it’s hormonal emergency contraceptives and can have side effects. But changing your cycle is the intended action. If you feel there’s risk, take it. If neither came in contact with the other and fluids weren’t exchanged it’s not necessary but if the condom didn’t fit and you question it, take the plan b.