If Data notices her uncertainty, he does not give any indication of it.

What he says next might alleviate some of that uncertainty, however. "Those were my conclusions as well," he tells her. "It occurred to me that allowing Milliways to be overrun with Starfleet officers wishing to study such a fascinating temporal-spatial anamoly might be a violation of the Prime Directive. And because the appearance of Milliways is somewhat unpredictable, I also considered the possibility of not being believed, and having difficulty showing evidence to support my claim."

After a short pause, he suggests, "Perhaps we should continue to keep this information between ourselves."