We've had our german shepherd for a few weeks now and all of the sudden the past few days he's become obsessed with smelling the grass. Before, we would let him out, he would go to the restroom walk around a bit then come back to us or lay in the shade. Now, he darts out the door and immediately begins sniffing the ground, he did this for 2 straight hours yesterday, does not come when called, and whines when you hold him away from the grass. What's the deal here? Side note: There are neighborhood dogs across the way, but they have always been there and none of this was an issue until recently.