PMB,
There is a ratcheting mechanism on the cam chain tensioner.
If the tensioner pawl has taken up a tooth on its ratchet when the engine is cold. The thermal expansion of the engine, which is about .025" between the camshaft and the crankshaft is too much for the system to accommodate. The poor cam chain is under tremendous tension at this point and will only be relieved when the chain stretches a bit. This happens whenever a tooth is taken up on the ratchet mechanism when the engine is cold.
You can see the tensioner on 'The Motorcycle Handyman' which can be downloaded from our website.
I believe Verslagen has come up with a fix for this problem which should help to extend cam chain life.