IBM V3700 Easy Tier Statistics

I have a StoreWize V3700 SAN with Active Easy Tier

I need to expand a clustered volume which has our production critical databases, the most active volume on the SAN.

Question is if I expand this volume do the easy tier statistics reset and move the volume away from Tier 1 until such time new statistics are collected and Volumes reorganized across Active Tiers?

Reason I ask is it is critical the volume stays as Tier 1 (on the SSDs)