It's really dependent on the pickup design.
A standard issue single coil Jazz will have pretty even output across it's entire sensing width. The double poles end up so close to each other that the magnetic field is very similar to what you would get on a blade design.
Some other pickups with discrete pole pieces do have very slight valleys between the poles, usually on pickups meant for wide spacing with very small poles and generally weaker magnets (reliant on coil turns to get good output).
Then there's split coils, ie humbuckers with two short coils such that each is under half the strings. These have a very significant valley between the coils, often dropping off to effectively zero output. This is why you can't use a split coil 4 string pickup on a 5 string bass - the center string is silent.
Without knowing the pickups in the OP's bass, it's hard to say if there will be a problem or not. It's definitely true that most people freak out wayyyyy too much about pole to string alignment, and for the most part small misalignments are absolutely harmless, but swapping string count or making huge adjustments to spacing are the cases where you can actually run into problems depending on the pickup design.