So she already knew of his presence in Milliways. Intriguing. Data finds it understandable, though, that she did not approach him with the issue.

"I am curious," he says, folding his hands on the table. "Why did you choose not to report the existence of Milliways to any of your fellow officers?"

It is not a reprimand, merely a question-- after all, Data also refrained from making an official report. He is simply curious to hear if Sariel's reasoning for doing so was similar to his own.

Then again, it is perhaps difficult to tell from Data's tone of voice whether he is reprimanding her or not. He so rarely sounds stern, even when he is offering criticism.