Mike, maybe those seedlings dislike the peat pots as much as I do!
If they are unhappy as they are, and not ready to go into the soil, maybe pot them up into something other than the peat pots, with a well-draining mix. Even a slightly bigger pot would make the roots happier if the soil or pot is the problem. Your mix looks nice and open, with all those bark shreds.
Slow growing seedlings that are not very leggy might well be too cold, and "back indoors" sounds like a good idea to try.
