Hi,
   Have they grown any new leaves while outside yet?  It may be,
the old leaves are simply unable to adjust to the sun and have
been burned...  I have not had much luck growing VFT in Sphagnum.
They generally like it a bit drier and 1:1 peat:sand does well.
Water from above before it dries out.  I have taken to growing
them in the same manner I grow Cephalotus but I don't let
Cephalotus stay out over the winter.  The one I tried last year
didn't even make it until the hard freezes before dying.
Dave Evans