Yes I used to get that all the time. I did have a lot of trouble getting pregnant when I was younger but doctors could never work out why - no tests ever showed any kind of abnormality, including the test you mentioned.

Last year when in a new relationship (and still getting spotting before each AF) I managed to fall pregnant 3 times and the last one stuck resulting in the birth of my now 4 month old son. The only cycles I didn't get the spotting was when I was pregnant.