Lost!

[Ghoulish Delight]

Originally Posted by Gn2Dlnd

I really, really want to know why Rose thought she recognized the sound made by the Smoke Monster.

From Lostpedia

During the DVD audio commentary on "The 23rd Psalm", the producers talk about the moment in the pilot where Rose says the "Monster" sounds familiar. They reveal that while searching for monster sounds for "Pilot, Part 1", they came across the sound of a New York City taxi fare printer, and decided to use the sound for the "Monster." This sound would obviously be familiar to Rose, as an inhabitant of the Bronx.

ETA: Of course, there could be a reason that they chose a sound that would be familiar to her, but it seems it doesn't sound like it's going to turn out that she had encountered the smoke monster before, just that the smoke monster incorporated something familiar to her.