What could be causing striations on the neck when using FL bushing die? Brass was cleaned and the bushing was removed and cleaned but still getting small striations. I've used the same die (whidden) for at least 1000 rounds but this striation issue just started.

Sounds like the bushing is scratched on the inside. Once they are scratched, that's it, they will always be scratched. It's from sizing on uncleaned brass, or brass that has something on the necks during sizing.

Mine do that when there's not enough lube

Sounds convincing but for this particular round first, I clean, anneal, polish necks with steel wool, then size using lube. I also inspected the bushing and couldn't see any scratches.

Are they very deep, or very slight? Some of mine have made very slight striations. Fine enough someone over 45 probably can't see them without their readers.

45 isn't far away for me but my eyes are still hanging in there, I think anyway. The striations are faint and come out with steel wool. I'll order a new bushing an see what happens.