I'm not sure I see what you're describing, but it's unlikely to be gravitational lensing. That requires truly massive gravitational fields and distances to have

I'm not sure I see what you're describing, but it's unlikely to be gravitational lensing. That requires truly massive gravitational fields and distances to have a noticable effect (eg. large clusters of galaxies). It's probably more likely due to gravity causing stars/dust to drift towards each other, causing clumps and voids.