Interesting how I felt that way with a woman with real promise for an R, but not from the more shallow connection.
It's good that you see that. I'd think that the "shallow" connection isn't threatening because you know the "threat" of intimacy isn't there. Meaning that, with her, you've decided there really isn't a relationship looming nor will develop, and so you don't have to deal with opening yourself up and being vulnerable and taking a risk again on love and committing to a person. Or something like that. Whereas with the stunningly attractive professional woman, you sense there's that possibility.
Go slowly and evaluate. If things are right and work nicely between you two, it will be comfortable and you'll feel safe and secure. Then, it won't be a matter of fearing what may develop, but of enjoying what is developing.
While that's happening, kindly pass me the other gal's number.