About my delicate feelings

Last week, we had a co-worker -- who usually telecommutes from afar -- in the office for a retirement visit. I, with the help of others, spent quite some time and effort planning and executing a couple of days' worth of various activities (lunches, dinners, reception, gifts, etc.) to make sure her last couple of days were good ones. I was having a busy week, so it all got squeezed in among the usual business.
Friday afternoon, as I was wrapping up my week's work, trying to get out a little early in anticipation of a busy holiday weekend, I heard her saying goodbye to a couple of people nearby and expected her in my cube any second. She never came. When I looked for her a moment later, she had left.
Instead, when I got my email over the weekend, there was a brief note addressed to everyone in the company saying thank you and that she was "overwhelmed."
I was underwhelmed.
Now, I'm a grownup ... I don't expect a dump truck of thanks or appreciation over every little thing. But tell me -- doesn't it seem to you that if you'd been hosted and toasted for two days by people you've worked with for over a decade, you'd make an effort to pull yourself together and at least say goodbye, if not, thanks? (Please note, I was not the only party planner who did not get a chance to say 'bye.)
So, you tell me: am I expecting too much? What are you thinkin' about showin' some love to others?