There are multiple presences in the Force on Coruscant that would count as strong. Luke has begun to pick up on all of them more on instinct than as anything conscious - the timbre and the feel, so to speak, of each one even if he’s not personally familiar with most of them. So the girl grabs his attention almost immediately. He doesn’t know her, which isn’t surprising. He’d like to get to know her.
He’s started to connect her to some of the rumors, especially those from the younger (or - well, what does that even mean any more?) generation - that is to say, the one more familiar with the Resistance and the First Order. But he hasn’t wanted to pry too much. Expectations are not what he wants to place on her, especially not from him.
Luke knows who he is and what he represents and sometimes that matters more than what he thinks of himself. So he waits to approach her until there’s a rare moment of quiet, most of the base distracted with everyday workings, to approach her. And he picks his words carefully.
❛❛ You’re Rey, right? I’ve heard a lot about you - all good, I swear. ❞
There’s been faint implications that he met her before, an older version of himself that he certainly isn’t. It’s an odd thing to know walking into this conversation.