Venison Salame success with one small issue

As you can see by the pictures, the venison salami were quite succesful...........to an extent. The texture is perfect. The taste is very good as well. Garlic, but not too much so. A backdrop of red pepper without being "hot".(A lot was used) Salt content is dead on. Even looks pretty good, too!(I have a slight bias). Anyway, as you can see by the top left picture(had to be taken on a paper towel) I had a slight issue. I'm hoping someone can chime in here. Usually when I make salame and/or salumi using collagen casing, the casing will adhere to and shrink with the particular product. With this salame, I noticed that wasn't the case. The venison salami did develop the usual mold, but didn't "shrink wrap" like it usually does. I didn't go by weight with this salame, because Len Poli's recipe had it being pulled at 25% weight loss. When I pulled one out at 25% weight loss, it was nowhere even close to ready, so, I would go by feel. Well, I pulled one out and cut into it, and this is where it gets a little confusing. It appeared wet between the casing and salame, but not water wet, grease/fat wet. It looked lubricated inside, which is why I would guess the casing didn't adhere properly. I'm puzzled because the venison was extrememly lean, I didn't cut anything off of it, no sinew, fat, nothing. It was so lean I went 30% fat, which isn't abnormal even when using a fattier cut of pork. The salami all seem to be fine, just have to wiped down with a paper towel. These salami were cased in 43mm collagen casings. Lonzino to be cut down tonight!