I think we need to separate the systems out now! The MBTI test is tapping into the Big 5 dimensions and isn't terribly Jungian itself. It isn't surprising for someone who scores I+N+F+J consistently to be very good with details.
Part of the reason for that is I'd say being good with details taps into Conscientiousness, the Big 5 dimension corresponding most to J. They're more particular, exacting, etc (than the scatterbrained people like me).
Now, if we want a purely functions-y concept of sensation-intuition, that's a project of its own right to properly define. One of the things is that S-N taps into Big 5 Openness to Experience, yet there's no inconsistency between being a sensation dominant type in a functions-y sense and being high in that factor of Big 5.
One of the interesting things is you can slightly swap and rearrange a lot of things to make a new version of the same system (no different from choosing alternate coordinate axes to generate 4-space or 5-space from). Of course, the conversion between standard MBTI test and Jungian stuff isn't this neat, but the conversion between say, Big 5 and one of its competitors is pretty neat.
In my experience, this sort of rotation is going on between functions and the traditional MBTI. I think, between Js and Ps on the test, Js have a lot more chance of seeming "sensation-ish" -- Jung's disciple described N-S as the former being more flighty, abandoning projects before they were finished, bad with details and mixing up facts, whereas she described the sensation type as great at all this.
A J IN THE TRADITIONAL MBTI TEST sense doesn't typically abandon projects, is conscientious, meticulous, keeps schedules, etc (or at least has a subset of these traits).
All this concerns more life habits. It's not at all strange for someone to be like that but prefer more imaginative, unconventional, out there, theory, etc stuff. How they are in their life habits on a basic level vs what excites their curiosity are two separate things (hence why N-S and J-P are, while sharing a bit of messy intercorrelation, mostly independent factors).