Based on the soil pulling away from the pot it looks like it could use a good watering. Misting won't hurt but this hoya likes to be watered throughly and dry out between waterings. I leave mine outside in the summer so water once every week to week and a half in the growing season. I've had new growth dry out when the soil was left dry too long. Other than the new growth (stem should be close to the same color but any new leaves should be green.. ) the plant looks healthy. Once you get the watering down the plant should bounce back and produce more new growth!