The initial misidentification Misha could forgive, but the fact that Bella couldn't tell it was him after looking right at him, put Misha off. When you were born into a family of almost entirely wolves, if was natural to be able to tell one wolf from another. His head cocked to the side and he was about to bark his protest, when Bella began to touch him. To Misha, being scratched and petted as a wolf, was a lot like getting a massage or his hair tugged at when he was in human form. Put simply, he enjoyed it, and the fact that Bella was the one touching him made it so much better.
Misha gave an appreciative "Browwowow" sound, and leaned heavily against the touch. There was no doubt in his mind that Bella had the experience with wolves that she claimed, because no one had this much natural talent. Somehow Misha had kept from getting too excited at being in her presence, as he was simply in shock at the fact that things were going so smoothly. Of course, that wasn't likely to continue forever. There were some distinct differences between boy wolves and girl wolves, that evn Bella had to notice eventually.