With the sudden outburst about the size of the clothes, the Doctor laughed a little, almost a nervous sound, but he was stopped short by her asking if he looked at her, ever. And his smile slowly faded, watching as she violently dried her hair, then dug into him again with the dog comment.
But then, his smile had certainly disappeared and he was left just staring at her almost in disbelief. Where had all of this anger and sudden aggression come from? What had he done? He didn't even know! But unprovoked anger never sat well with this regeneration, and now was no different. His disbelief quickly changed into a defensive expression and he narrowed blue eyes slightly on her. "I did the best I could with what was left in the shop. And no, Rose, I don't ever look at your.. size." He did, actually, but wouldn't admit it. That meant he had some sort of non-platonic feelings for her, didn't it? And he didn't. Definitely not. Nope.
"And I'm not calling you a dog, I was just happy to see you were safe and sound. I come back, and here you are, and I'm happy to see you, and you start off with this? I thought I told you to leave the domestics outside." The Doctor didn't do domestics. And this? This was a domestic. In the most literal sense.