There could be other reasons that affected the decision for the wage for your coworker. It might be that we are in a recession at the moment and works are not

There could be other reasons that affected the decision for the wage for your coworker. It might be that we are in a recession at the moment and works are not that plenty ( at least where i am ). Someone might have noticed something on your CV or on the interview and did decide that you were worth a bit more. Salaries have decreased dramatically in the company that i am in. Some position as 2 years ago is 300Euro lower. But i believe the right approach for that is the one that sweettea has mentioned. Casually bringing it up.