Just an FYI- Level 4 is now optional in CPE so you should not base any grandfathering on that.
This is the chart from the UKI rule book which is the only other venue that I know of that has grandfathering.
Transfer Table of Highest Level in Standard Agility New Registered Handlers Only
AKC/CKC USDAA/AAC CPE UKI International Program UKI Speedstakes Program
Novice Starters Level 1, 2, 3, Beginners SS Beginners
Open Advanced Level 4 Novice SS Novice
Excellent Masters Level 5, C Senior SS Senior
Masters MAD N/A Champion SS Champion