One thing that is different on my system is
that I did not use the factory hoses. I went with small light stainless braid
teflon hoses.  They are good to 3k psi. The system is tight, tight, tight. If
you went with the factory hoses  it may be acting like a balloon and expanding
a little. Can't remember if you have gauges on your hyd system but that tells
the story of what is happening, not necessarily why though...

Randy,

 

Excellent point on the flexible hoses.  I have not had the  lockup problems under the similar conditions that some have mentioned and I have the original Easton hoses installed (circa 1989).  Perhaps those with cold-->warm lockups would volunteer information on the kind of hoses they are using.  It sure could be a possible explanation for that problem.