"To GET your fingers on..." is not a commonly used expression in my experience, so if had to guess the meaning of it in this sentence, I'd say it means as you said; to discover an interesting point and then feel the need to think about it deeply. There are two similar sounding phrases that are common though but have slightly different meanings: --> "to NOT BE ABLE TO PUT ones finger on it" --> "to GET ones HANDS on it" "I can't quite put my finger on it" --> this means you are unable to exactly identity or remember something. "I just got my hands on a great deal" --> this means to acquire or buy something.