Pine Warbler - In South Texas?

I was surprised to discover this was a Pine Warbler. I had it identified by one of the birding tour guilds from Santa Ana Wildlife Refuge. How could I argue with him!?! They don't even show up as migrating through South Texas in my birding book. I saw these everywhere in the Valley during February.

Date: February 2011
Location: Ranch in Star County but photographed in Harlingen as well.
Behavior: Not near as feisty as other Warblers. He seemed much more laid back giving me plenty of time to take pictures.