Isopropyl alcohol forming peroxides
I think this may be an overreaction.  First, MSDS are designed for workers working with industrial quantities in industrial conditions.  Second, the danger comes from concentration of the peroxide from evaporation or, more typically, distillation.  Small quantities of peroxides in solution are not usually an explosion hazard.  Third, I have never seen isopropanol listed in lists of hazardous peroxide prone chemicals as used by lab safety departments (ethers are the typical risk here).  The closest I have seen is sec-butanol, which is the secondary alcohol from butanol, and I've only seen this listed once, in a list that seemed much more cautious than some other lists.  Isopropanol is the secondary alcohol from propanol.  Given your storage, cool and dark, I think you are fine.  Remember that 91% isopropanol is sold in drugstores, though these may contain stabilizers and you larger bottles may not.

But having said all this, Lighthart's brief answer is correct though probably unlikely.  If you DO see any crystals, don't even try to open the bottle (crystals in the threads are the most common source of explosion).  But again, seems unlikely.

If you are still concerned, there are peroxide test strips you can buy that are very easy to use and can tell you what concentration of peroxides are present.