Update: My buddy in Flagstaff said my old sleeping bag was basically a 'cold trap'
I was camping near Sedona last weekend and my friend pointed out my 15-year-old down bag had lost a lot of its loft. He said the fill was probably clumped and creating cold spots, which explained why I was always chilly below 40 degrees. I never really thought about gear degrading like that over time. Has anyone else had a sleeping bag just stop performing after so many seasons?