Grady was pretty calm when I was leaving so I left them together. When I returned, he was calm, but upon picking up Wilber, I found out why. He had expended his sexual frustration all over Wilber's backside. GROSS! It took a lot of cleaning to get that out of his fur because he's got that long Peruvian hair back there. I also had to trim a tiny bit of it out. Of course he didn't like that at all. This is the exact same thing that happened when I first got them. Grady chased Wilber around until he got his way with him and then they got along great until this repeat episode almost a year later. None of my other board have ever done this. There's some minor mounting between them once in a great while, but it's very quick and there's never a mess like the one that Grady leaves on poor little Wilber.
They're getting along normally now. So it looks like this might be a periodic occurrence until they get through the hormonal stage. That usually happens around 2 years of age.