Like tyres, the bolts, nuts, clamps and screws on our bicycles should be regularly inspected and tightened.
Things wriggle loose with all the jarring a bike receives, and the weight and force exerted on it.

A loose bolt on your saddle does not necessarily mean it has to be replaced.
Tighten it, and inspect it each time you ride - if it stays, its fine, if it loosens quickly, then maybe you need to look at wear and tear maintenance.

Example... my bull horns/aero bar set up was wriggly the other day, slipping to a slightly-pointing-down position, so we made it parallel to the ground again, tightened the screws on the stem, and in 3 vigorous rides since then, it has not shifted...