Hi @ADuv & welcome to the Community! 
Did you turn off your data roaming while you were already out of Canada? If so, it's possible that your phone briefly used data, which would have triggered the charge.
If this isn't the case, let me know and I'll send you a PM to take a closer look into your account. You can also contact us on Twitter or Facebook for any account-related inquiries.
Cheers!
