I have. I am a member on About.com...they have a headache/migraine forum there and I have heard of people having symptoms of migraine without head pain. That might be what you're having. I don't pretend to be a doctor or anything of the type. i would suggest talking to your doctor and doing some research on your own.
Are you having other symptoms other than memory problems? How about medications, are you possibly taking something that is causing this as a side effect? Just things to think about...
For example, I was taking Topamax and had a horrible time with my memory and speech and didn't realize that was part of the problem until someone else mentioned to me they had the same problem and we figured out that the meds were the same in both situations.
Take care and feel better!