Does that mean that Star Trek sensors are, for whatever reason, are unable to detect objects with a lot of mass while in warp?PICARD: Why didn't we detect this before now?
DATA: The objects enormous mass is creating a great deal of gravimetric interference, that might have prevented our sensors from detecting it before we dropped out of warp.
This would be particulary interesting, because Star Wars has means to create "gravimetric interference" with their Gravity Well generators, commonly mounted on small cruisers.
This could potentially be used to stealth against ships that fly patrols at warp - oh, and it is a very good point against warp strafing, too (not that we ever see it in the first place).
Of course, the Empire does not need to be sneaky - but it's still interesting.