Brake lines

When I replaced my sway bar bushings this past weekend (which, BTW, thanks to all who have contributed re: that fix...its soooo nice having a 9 year-old van that has the "new car" thump when going over bumps instead of the "beater car" clunk) I noticed a fitting that seems to distribute the fluid to all four wheels...located behind the drivers side bushing...it looked like it was a popular location for rust. Just to be on the safe side (my wife is the regular driver of the van...usually carting around my 2 year old) has anyone had to replace any of their brake lines because they rusted out? My BIL has a F-150 that had the lines rust out real bad in the back...they dont look THAT bad...but...I was just curious.