Make sure you inspect the whole length of all the lines. They rust, and if your fluid is rust colored some of that may be from the lines. The other thing is that they do get pinched sometimes too, people put jacks and jack stands in dumb places and if the lines are original there's been lots of opportunities for them to get damaged in that time.
If on inspection they look ok they're probably fine, but, you don't just want to assume they're ok.
