I got a warning in lower left side when I started my wallet today. 

WARNING: Checkpoint is too old. Wait for block chain to download, or notify developers.

Wallet says it is synced and up to date, block explorer shows same block height.  I tried closing and restarting several times but still same warning.  It was fine when I started it on March 17th, a couple days ago.  Should I be worried about this warning or can I ignore it?  Wallet version is v2.0.4.0

Thx