Brian-
Welcome aboard and welcome back to the tying bench.
Your question is a good one. I have had experiences with herl drying out and have some hackles that I picked up that were very brittle. Unfortunately, I think the only way you are going to be able to figure it out is to use it, if it is continually giving you problems then I would say toss it. Give your hands a chance to get back into tying shape. You could be snapping off a lot because of too much pressure, etc.