Delta shower facucet in a new tile shower

Installed this in a new tile shower:

http://seek.autodesk.com/product/latest/agg/delta/DELTA-Faucet-Company/15560

And every night I dry the shower to keep it spanking new after spending all that money to replace the old one that never was dried and looked terrible.

The question is I never caulked the faceplate on the shower faucet to the tile. I was thinking that the faceplate handles the water that gets behind it with that ring of Styrofoam. But watching this last night after turning off the shower I noticed beads of water getting behind the plate at the tile grout lines. I caulked my old one and thought it looked bad and the caulk tarnished the trim over time also.

So, can I leave it as is or do I need to caulk it?

Thanks, Tom

We use clear polyseamseal when we caulk.
I never trust only the seal behind the plate.