Are you powering up the caps separately? OR the whole unit??
If the latter then you may put more demands on it as a whole with the lower voltage. I don't THINK 4 years storage should have had any detrimental effects (but it's a dielectric device) but if they want to go BANG they will.
Be very careful with any tinkering you do, they are supposed to be designed to discharge slowly back through the circuitry, but if you power up/down then decide to tinker you could be exposing yourself to some quite high voltages, although probably not in the same magnitudes as those found, say, inside your humble micro-wave. Now they are dangerous.
GR.