Do not let them experiment on your cel! :)
I advise like the previous poster, do a lot more
shopping around.  There has got to be 
another framer in your town besides 
Michael's.  If there isn't, wait for one or look
into another town.  As the previous poster
mentioned, UV glass is essential as are
mats.  I recommend at least 2 so the cel itself
does not touch the glass at all.  Also, make
sure you seperate the sketch from the cel
before you do frame it.  It will look better and 
the acid from the sketch paper won't leach
into your cel.  If you would like to see 
examples of my framed cels, check my page
under the "Cel" section.  Please let me know
if you have any questions and if you don't 
get a good vibe from a framer, keep looking! :)

Jen