If it keeps happening it will quickly run your battery flat so i advise you take the fuse out when not using it. I plan to install a seperate switch that hooks into the existing fuse position on my girlfrinds car and then mount it on the removable trim that covers the fusebox. Heres how:
1. buy a blade type fuse holder from maplin
http://www.maplin.co.uk/Module.aspx?moduleno=24539
2. buy a switch with male spade connectors (also maplin)
http://www.maplin.co.uk/Module.aspx?ModuleNo=2363
3. Crimp a female spade connector to one end of the fuse holder (extending the wire if necessary, so it reaches your switch mounting position).
4. Take a new piece of wire and crimp a female spade connector to one end and a male spade connector to the other.
5. now also put a male spade connector to the piece of wire from the other side of the blade fuse holder.
6. mount the switch in the removable plastic panel that covers the fuses
7. plug the two female spade terminals into the male terminals on the back of your switch
8. Remove the existing centre console fuse and place it in your new fuse holder.
9. plug the two male spade connectors into the slots where the fuse went originally.
10. replace plastic trim
You can now switch off your headunit without removing the trim and fuse every time