When you're married to a chick as hot as GWEN STEFANI, your eye should never need to wander, right?  As any married person will tell you, nothing could be further from the truth.

It's not about who's hotter . . . it's about who's NEWER.  And often, who's YOUNGER.

GAVIN ROSSDALE took his sons hiking in West Hollywood over the weekend . . . with the help of a young, blonde nanny.  And the paparazzi caught his hand wandering dangerously close to her BACKSIDE.

And that brings us to today's YES OR NO?  We want to know:  Is Gavin's hand traveling OUT OF BOUNDS . . . or is this just an INNOCENT TOUCH.