I certainly would not think your shocks are needing to be replaced unless you had handling or ride quality issues. We bought our 2002 in '05 with 31,000 miles and felt the ride was a bit harsh. In '06, I replaced the OEM Bilsteins with Koni FSD shocks and felt an improvement in the ride quality.
If you ever want to really improve the way that Freightliner chassis handles turns and uneven road surfaces, consider installing the Super Steer Motion Control Units. These are fairly simple restrictors you place on the air lines near each suspension air bag. They really make an improvement in the way the thing corners and handles. Plus, they minimize the 'Walmart Whip' or the sharp snap back and forth when you enter or exit parking lots.
Bottom line, you are satisfied, I'd wait until you get some evidence of worn shocks....that should be many miles down the road.
2007 Country Coach Allure Siskiyou Summit, sold/traded Nov. 2018.
2019 Grand Designs 384GK-R 5th wheel. Glen Allen, VA