I'd say, if your springs are over 10 years old you might as well change them. It's a cheap and easy fix that could stop a disaster from happening. I changed mine when I bought my CVX three years ago. They were $35 each with all new mounting hardware and U-bolts for the axle.
Luckily, my brother only burned off about 20,000 miles on the tire that rubbed the inside of the fender at 70 mph for about a minute. He was able to limp it to an entrance ramp about 200 yards ahead and use the shoulder there to work on it. At least he wasn't on the shoulder of the actual travel lanes going 70+. Got the broken spring replaced (had a heck of a time getting the original bolts out). Towed it 5 miles to the next exit and was able to use a truck stop canopy to change the other one.
His normal 7 hour trip that started at 8 AM from my house ended up getting him home at 11 PM.