Sometimes after being on f/t for a long time, they get bored, understandably. Live feeding helps them get back on track again and maybe after a few good meals, he'll switch back. My first snake, Amani, started out on f/t rats. At around 7-800g, she just got bored and stopped eating them, for months.. She's been on live mice now ever since then(she's an 04 and is 2000g) and is doing great. She's actually about to ovulate soon too