No, but I too I have a healthy paranoia that it's possible. In fact it's almost guaranteed your going to leave something behind. Sunglasses and hat being the most common left behind items. But there are some scenarios where you can lose your gear and or have it destroyed.
Let's assume you're four day's into a eight day trek through the back country during the summer time in a heavily forested area such as Wyoming/Montana/Michigan/Canada/Alaska etc. I chose those areas since they have Grizzly's, fast running streams, sudden storms, low valleys and high mountains, wolves, severe storms that come on fast, etc.
If you have all your gear including your knife and fire starter inside your pack, with the only thing in your pockets or belt being an Ipod, you run the risk of it losing everything but your clothes and Ipod if;
You fall into a fast running stream while trying to cross and some how lose your pack. Whether it's knocked off or taken off, either way it slipped from your grasp and was carried downstream to who knows where.
Your in your shelter or tent when you awake to a severe storm that quickly floods your area. You quickly dress and stumble into the dark for high ground and forget to bring your pack. It gets washed away.
You have to climb a tree to avoid an aggressive grizzly and feel you can't climb whatever tree you find without taking off your pack. The grizzly leaves you alone but not after tearing through your pack and destroying most of it's contents just to get your food.
You take off your pack to stretch and enjoy the sounds of nature. Maybe relieve yourself, or sneak in close to some animal for a picture. You then forget where your pack is.
We can go on, but the point is losing some or most of your gear happens all the time. People make mistakes and accidents happen. To prepare you can be redundant with the absolute essentials. Not "two tents" or "two sleeping bags", but small and light essentials secured to your person at all times. We all have our own preferred methods. I like to wear a fisherman's vest with essentials distributed throughout the many pockets. A fixed blade knife on my belt or possibly strapped onto my leg, but not strapped to my pack or inside it. I think it's important to limit it just to the light essentials or you may not be willing to wear them all the time. What I really like about the vest is that I can comfortable sleep with it on, or at least sleep with it side my sleeping bag. How many of you would be comfortable sleeping with a becker necker around your neck and a large fixed blade on your belt while sleeping? If you are, your more hard core than most.
