The fact that you got paid at all suggests that they do have your details correct. I don't think it's common to pay for online training, rather it's just part of the job that you have to do. I also think technically it's illegal to have training and not pay you for it, but induction might be different to store orientation. They should have stated in the interview when they talked about what the next steps of the process towards working there are, which parts you get paid for and which parts you don't.
If this continues to worry you, just contact your supervisor, or the HR department.