It might be because of shift in your ear wax. We should all get ear wax cleaner from a drug store, and clean ours - most cost effective tweak.
Also it might be your body condition. Some audio lovers would actually get up and exercise to be in top condition for their listening session.
I find audio a great help in exercising - with a sub going on a pop music with heavy drum beats, you don't feel the pain.
Anyway, I found that if you assemble a liquid sounding system, then those special moments happen more often. You can enjoy music right from the beginning without having to warm them up.