Ive had fish bagged for 12 hours before... as long as they get a few air changes, and are kept to temp they are fine, BUT - they will need aclimatising VERY slowly at the other end.
On this occasion I placed the bags in a "cool box" and added a little warm water OUTSIDE the bags every couple of hours.
Lets face it, fish get posted world wide, and dont recieve this attention ! so a few hours should be nothing to worry about !