If his awareness and behavior was any indication, the dragon was beginning to take his opponents more seriously as a threat. He was not leaving himself open to attack as readily, and was watching them more closely than he had at the beginning of the fight. He noticed Sabine, and more importantly, the spell she had charged. 

For a few moments, the dragon kept his head low, growling at Sabine. However, he knew he could not simply refuse to act while the others were recovering. As he turned his body towards Sabine, he swiped his tail at Yerig and Do'rhajul, then started to charge right at Sabine, watching for her spell all the while.