WUS is right, until a formal diagnosis is made there is no pre-existing condition. We ran into a similar snag when my mom died, stating that Alzheimer's was pe-existing(non-diagnosed prior) even though she had the policy for many years before she died from complications of it.
A simple threat of contacting the above agency did the trick for us.
Good Luck with the heartless POS that are our insurance companies...as if people don't have enough on their minds...they gotta fight for what is rightfully theirs...