It wasn't Hank having anything 'against' Josh, persay. It was simply that he didn't want Josh to face potential disappointment should he not succeed. Hence Hank's hesitation, he shifted and seemed to mull over the question when Bobby appeared.
"Hello Bobby, hello Jonah," Hank greeted the two with a (closed mouth because the fangs tended to make a bad impression) smile. He crouched down to the balls of his feet to be closer to eye level with his young patient--it made people feel more comfortable and Hank was painfully aware of how intimidating he could be. "May I?" he asked, before carefully taking the scaled arm in his hand. "Yes, it does appear you've burned yourself--Jonah, if you're feeling chilled, you're supposed to ask for your room to be heated, remember?" But it, as most things, was said gently, kindly. Hank would recheck the chart after to ensure that it was detailed specifically.
"Josh?" He asked, looking up. "Why is treating our friend Jonah here different than treating Bobby?"