Leonard was concentrating on his work (and wondering if he should give the man more fluids because his sodium levels were still low), so he didn't anticipate anyone bothering him. The tug on his shirt, therefore, caught him basically entirely off-guard.
And there was his little patient, Julie. Immediately McCoy's brows furrowed and he opened his mouth, preparing to ask her if she was experiencing more pain or other symptoms, when she cut him off with a question. Right. Nothing more than a childhood boredom then.
Well, on the one hand, he was relieved she wasn't hurt. On the other-- he was rather busy, being the chief medical officer and all. Still, she had such a sweet and innocent face. Leonard figured he'd just answer her and hope that was it. (Yeah, right.)
"I'm checkin' on this fellah," he explained, pointing to his patient with the PADD. "Earlier we gave him some medicine an' I wanna see how well it's workin'." McCoy put on his Serious Face. "Now I thought we agreed you were gonna wait for your brother on that bed over there..."