Could have been convicted in your absence and fined.
In which case pay the fine and it will be over.
The Magistrate could also have issued a warrant for your arrest as you did not appear in Court; in this case if you cross the border and come into contact with the NSW police, and they do a warrant check on you, and see you have a warrant out for you, then you are taken to the police station and locked up until you appear before the Magistrate, which hopefully will be that day if they get you early in the morning, but if they pick you up in the evening then you spend the night in the cells and go before the Magistrate the next day.
Unfortunately if there is a warrant out for you, you can't just turn up in Court and ask the Magistrate to deal with it, you have to go through the process of being locked up by the police first, and remain locked up till you go before the Magistrate.
This needs to be changed, as if someone is prepared to hire a solicitor and attend Court voluntarily to have it dealt with, then they should not have to go through the process of being locked up first, especially when the penalty imposed may only be a small fine anyway.
Didn't they bring something in several years ago, where a charge in NSW can be dealt with in Court in Qld, and vice versa? Thought I read that in the paper some time ago.