Reading through the comabat example in the rulebook the wood elf hunter decides to move his stance meter 1 step deeper into the conservative stance and takes a point of stress to do so. This could very well be me as I have only read through the book twice now and one of those times was fairly cursory, but I cant seem to find any place in the rules that states that you can choose to take a point of stress to advance a character's stance deeper. I am just curious if this was like the need to prepare being a mistake in the example or if its actually a rule and where I might have overlooked it in the rules?

It is a rule in the rulebook. I don't have my book in front of me to give an exact page, but I believe it is right there in the start of combat turn steps where it also says a player may adjust their stance 1 space for free.

Just like a player may gain fatigue to perform multiple maneuvers, a player may gain stress to alter their stance additional spaces.

Page 57 under "Beginning of Turn Phase"

Great thanks very much I found it on page 57 in the small paragraph at the end of Begging a Turn Phase, I must have missed it or my hand was covering it. Either way I really apprechiate that it was the only rule in the main rules I hadnt been able to cross reference from an example and Im running a demo game for some folks on Sunday and wanted to make sure I had the core rules down soundly before then.