Long-Term Amp Storage Without Use: Bad Idea???

Hi All.  I've got a nice set of Cary EL-34 tube monoblocks which I haven't used for 2 years.  I put them up for sale, but then decided I'd rather hold on to them for a later day.  That later day could be years from now, maybe even a decade.  I don't expect to pull them out and "exercise" them to keep them in shape.  Is this a bad idea?  I've heard capacitors tend to dry out if left unplayed for too long. Thanks in advance to those who have knowledge in this area.