Re: movement in new fence posts
Flexing of the post and rails is irrelevant, movement of the post in the ground is unacceptable. The caveat to that is whether or not the ground is firm enough to hold a post solid. Saturated ground is not conducive to immovable posts, this doesn't mean the fence is going to fall over, just that there will be some movement until the ground dries out and firms up.
Other things that can affect the post is whether it was dry packed with dirt, gravel, cement, or if it was wet set in cement. Not compacting the fill around a post enough can cause a loose post, again, not a big issue as long as the dirt is allowed to settle and compact around the post.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!