timing chain replace or wait 2.7L

[47silver]

I am hearing a slight noise on start-up that goes away when warm.
I took the cam chain covers off.
Incidentally it is an easy task to do once you remove the muffler. in my case i had to dremel 3 nuts off and loosed the 2 clamps. (30 minutes).
makes adjusting the valves a bit easy too.

The Motor has about 40000 miles on the rebuild.
It was machined and aligned bored to standard.

I tried to press the oil tensioner and found it to be very tight and seemed to be working properly.
However the tensioner is at the top of the stroke (i took pictures but they were not good enough to post).
my questions:
does the case expand when hot and will the chain get looser or tighter when this occurs?
should i replace the chains?
if i replace the chains do i need to replace all of the sprockets?
other than this noise the motor runs great.