I’m a New Guinea pig owner and I’ve had my boys for about 3 weeks. They are said to be 4 months and one relentlessly humps the others face. I understand this is to figure out the hierarchy, but today I put them in their new C&C cage and the “boss” pig started humping gus. When I lifted the hide I found this gooey clump. Some of it was also stuck to Gus’ face. Any idea on what it might be?