Yeah, the weird warping was worrying me, another reason to
replace most of my cel bags (boy that Mylar is thick. !!).

I completely forgot about ambient atmosphere [duh], I'm 
lucky that Colorado is quite arid. I don't seal any of my 
cel bags (unless I re-use the sealable ones), but I keep 
everything in celbooks, too. 



About separating multi-layer cels - most of my cels were 
separated by the seller when I bought them, but I have two
cels from the same sequence (one after the other), both 
three-layer cels, but one is completely stuck together and
the other has been separated. The thing is, I can tell that
the separated one had been separated somewhat by force, as
paint had come off on the different layers.

I assume that forced separation of multi-layer cels not
only depreciates the value, but quite possibly will ruin the
cel, right? Is there a way to separate cel layers nicely? 
(Probably not.) Well, I guess I'll keep the better looking
cel. :P