I wouldn't have any concerns. But I would inspect all the silicone beads very well. Look for air pockets / bubbles in the inner beads (the thin layer between the panels). If it was stored on a flat, level surface it shouldn't cause an issue. Being in a shed, there's also the possibility that mice may have taken a liking to the silicone, but that would be visible immediately. After a good rinsing, a wipedown with peroxide would be a good idea too.
"Why can't my wife see all of this stuff as an investment?"