Many Heliamphora achieve that color in the presence of sustained bright light while other clones may remain greenish in the pot next to them (it varies). That reddening response of the anthocyanin pigment is also thought to be a protective measure on the part of the plants to avoid "high light stress" or photoinhibition -- a "sunscreen" after a fashion.
Considering where these plants are native and at what altitudes, it doesn't come as a great surprise . . .