I also made Mary Karlin's Farmhouse Cheddar in a stainless steel mold, so when it discovered the morning after pressing that it hadn't knit well (on the ends especially), I just put a heating pad on low underneath the stainless draining plate. That provided enough heat to knit the ends as well as the sides to a lesser degree (wrapped the sides with a light towel in an attempt to retain some residual heat coming up from the bottom). Because I waxed this cheese, the lesser knitting on the sides didn't affect the end quality of the cheese.
I consider that last technique a more desperate move, and agree with others that pressing in the pot over warm water is probably the best solution. At the time I hadn't yet learned that technique and now know that a heating pad can be a wonderful saving grace if I ever need it again.
tnbquilt: I also made the Just Jack, and despite the low weight pressing, it turned out to be one of my best cheeses ever! Sometimes you just get lucky I guess :-). I've had good results with her book, my first book, and have made around 20 cheeses so far. I'm excited to begin sprouting out a bit and will get Gianaclis Caldwell's book next.