I do it to with my T, and for me it's preemptive also, though in a slightly different way.

For me, I'm super-ashamed of feeling like I want things from my T or have needs I wish she'd fulfill, particularly because those desires generally stem from unmet childhood needs. So, whenever we get around to talking about those sorts of things, even in a tangential sort of way, I start talking about how crazy I feel.

And it does feel a little crazy, because while I mostly feel like a 4 year old in T, in reality I'm an adult. So the needs feel really shameful and embarassing and wrong.

So, telling T that I feel crazy has become my shorthand for "OK, I'm going to tell you about this thing I want from you, but I want you to know that I know that it's not in any way based in current-day reality. And although I really want it, I also know that it's not your job to give it to me." I reject the need right up front (by calling it "crazy") so I don't have to feel the pain of her not meeting it. A little crazy in itself, yes, but in a self-preservation sort of way.

And of course, the genuinely crazy part is that I label those needs "crazy" because I really worry about what T thinks of me, and I want her to like me and find me competent, etc. I want her to know that I "get it," or whatever. Because then some tiny sliver of me thinks "maybe she'll love me if I tell her that I know I can't expect her to love me." Because, to go back around the circle, the way to be lovable--or tolerable, anyway--in my family was to be totally self-sufficient and not have any needs to begin with.

Holy crud! Did that help any?