Mod Organizer listing Update.esm as "dirty?" (SKYRIM)

[Repiru 0]

So I downloaded SkyUI for my first mod to pass the tutorial for the first time opening MO. I then sorted it out using "sort" button which is LOOT. After that I noticed a light bulb flag saying Update.esm is dirty. Why?

[Greg 60]

https://wiki.step-project.com/STEP:2.10.0#2.B._Clean_the_Update_ESM