My Bilsteins only squeak during cold temps below 70 degrees or so. Very loud when it's extremely cold and gets quieter as I begin to drive around and warm up. When it's spring or summer like right about now, there are no squeaks.
I would try some silicone grease spray on the suspect strut. Spray lightly on the actual rod. It does help remedy the issue. For how long this will last is another question. I do this sometimes in the cold weather if I drive it alot. This seems to be the only issue I have had so far with the shocks. Otherwise, they are not bad at all. I would probably try Konis next if I had a chance, but my particular set have the Dali coilovers, so I am a bit torn by the value of this set.