To recap from the RAW, under special abilities/invisibility :
A creature can generally notice the presence of an active invisible creature within 30 feet with a DC 20 Perception check. The observer gets a hunch that “something's there” but can't locate it or target it accurately with an attack.
The following mods apply to the base DC 20 to just “notice something's there” :
In combat or speaking : –20
Moving at full speed or faster : –20
Moving at half speed : –5
Not moving : +20
[These mods are just some of what's in the table in the SRD. They ALL *modify* the base DC of 20.]
From the RAW under the Stealth skill description :
"If you are invisible, you gain a +20 bonus on Stealth checks if you're moving."
If we were to add the above information to the set of mods above, then to STAY CONSISTENT with the entire table's concept of “modifiers to the base of 20”, the entry would be :
Moving with Stealth : + Stealth check
Not "20 + Stealth check" as it is in the SRD.
It seems for consistency and clarity, either the table entry should be modified, or the table entry should be removed and Stealth addressed separately in the text of Special Abilities/Invisibility.