I see shrinkage in the fat, and I think some shrinkage in the meat, along with color changes, so things are definitely happening.
The humidity spike could be due to the moisture coming out of the meat. You might not get any blood drippings, and this isn't necessarily an indicator of anything bad or done wrong. A fresh kill would drip quite a bit, something bought from a supermarket might not. This does not mean it's old, just that it was handled and processed differently. Besides age and moisture content, it seems logical that depending on the condition of the natural membrane found on the meat would have an effect on the amount of seepage.
