My fiddle, which was my father's concert violin (and he was good) has to be 'woken up' sometimes - possibly a temperature/humidity thing - and the wave pattern theory sounds eminently sensible.Can take a few mins for it to get going - and yes, it does seem to warm up after a while. On other occasions it starts straight away... It doesn't like the cold, and I won't get it out on a campsite at night, even if there's a loud, permitted session going on. I used to, but it really doesn't like it so I've had to realise it knows best. I won't cross-tune it either, nor have a pick-up on it, and I really try not to get rosin build-up on it either.