You might want to save that little lecture for the features that AREN'T explained like this when the phone is first used:
Yes, I saw that notice ONCE.
If a phone is activated at the store, most users might never see it.
The point is, the question comes up regularly in other forums, and even had its own Yahoo answer. A decent UI for regular users would explain it each time until the user specifically said "Don't show me that again".