[PLA object shinking during use]

That was exactly the answer I needed.  I knew I came to the right place.  Thanks guys.

[PLA object shinking during use]

I printed a replacement coffee pot lid with PLA.  The threads are 2mm deep.  After 3 or 4 uses (cycles of warm/cool from making/pouring coffee) the threads act as if they have been stripped out.  To the point that the lid will no longer stay in.  I have measured the diameter of the threads and find them within .1mm of spec.  The lid is never tightened, not even "finger tight".  It's just turned about half a turn till it stops, very gently.  The water is heated to 200' F but is cooled (an unknown amount) as it passes through the coffee grounds before it reaches the lid.  The pot is not heated.  It's a thermos type.

 

Can PLA shrink (further) after an object is used with the application of heat/cool cycles?