I've noticed that when I've received plants grown under lower lights than my conditions their new growth is redder, and also smaller, same as you. I've seen this in 3 or 4 different species, and it just seems to be the plant's response to high light. I worried about it at first, but as long as the plant continues putting out new leaves it's probably fine.
Hey you guys were saying that you never heard of growing petiolaris sundews in humidity as low as 25% but I came across this forum thread he claims that his plants are thriving in low humidity. http://www.flytrapcare.com/phpBB3/drosera-petiolaris-flowering-t21844.html