OMG, Echoes... imagine you DID bring this issue up at the very end of the next session? Hahaha.
Seriously though, you never do know what your unconscious is up to. Usually, it is up to protecting us, and as a result, knows that it is "safe" to release things right before it's time to run out the door.
It is interesting what you said about YOU thinking that what you brought up was not that important, but your T thinking that it was. I wonder if this is an issue of validation? I know that I tend to invalidate my problems and lots of times T will make a bigger deal out of something than I do! I will say, "What's the big deal about this?" only to later realize that I am completely minimizing and invalidating my own problem. I know that I do it because I have always existed alongside a "don't worry about it, it'll go away" type mentality. I guess because people around me didn't always take my "stuff" seriously, I learned not to, either.
I know that what your T said caused a big "ouch"-- but, I also admire that she was so direct with you. A good T will point out what they see-- rather than just saying, "Oh, we will open up with this next week," she pointed out a pattern that is very much worth exploring.
I know how much the waiting sucks. In the meantime, think about why it was a bigger deal to T than to you. It was probably a bigger deal to you than you think-- or else you would have brought it up at the beginning of the session!