This happens more with lenses, for me. In particular my 90mm Elmar. It's always in my bag, just in case, but ill rarely take it out. Then suddenly I will take a portrait or two, or see others' photos using it, and I will start using it all the time. Its fleeting, though; a 90mm has its uses, but it's just not an everyday kinda lens, at least for me.
My favorite part of using it with my Barnack is that i have to use the VIOOH with it. I get some crazy looks when I'm out shooting with that combo. People think it's an antique gun!