I wonder too if it related to some of the smells around. I hadn't quite made the connection earlier, but now that I come to think of it, my Sam drools profusely sometimes when I let him out the back. He loves to sniff around & feast of wildlife poo and this is the time of his worst drooling. I am sure this isn''t related to anxiety as it is his own backyard. So maybe it just smells yummy. Who know what gross delight may be found to eat at the park.