Agreed that it may have something to do with temperature, but not the temperature of the engine (coolant/oil)...temperature of the item causing the problem though, yes, to an extent. Or some other property which changes over an extended period of time.

I actually tried to change CP a few weeks ago because it was one of my main suspects but it was putting up a fight to come out and I just haven't had a chance to get back at it. Hopefully I'll have a little more time this weekend to get it out. Looks like I may have to crack the fuel rail loose to move it out of the way a bit as even with all the bolts undone (even the hidden one) it doesn't quite want to come all the way out.