Discussion about the Korg PolySix synthesizer

It just happened after I rearranged my studio: I put the polysix on 
the top tier of the stand, and was playing it for a little while and 
all was fine.  Then when I went back to it, I noticed my patch sounded 
kinda funny and out of tune-ish.  Then I realized as I hold the key 
down longer it acts all funny and adds modulation and shit to it.  It 
doesn't sound right at all.  What could be causing this strange 
behavior?  By the way, i did shut it down for a bit and turned it back 
on, same problem.  It's currently off until tomorrow.  Any ideas??