Your question made me go back and check my travel insurance policy and to do a bit of research. Of course every situation is different, but depending on the date that the policy was purchased, the look-back period of the policy, and changes to your health during that period, a pre-existing condition waiver may not be needed. I found this on a senior travel insurance site:
Travel insurance only cares about changes in your health 60-180 days immediately prior to buying travel insurance to determine a Pre-existing Medical Condition.
The Travel Insurance Carrier cares about:
New Medical Conditions
Changes in the Severity of an old Medical Condition
New recommendations for treatment
Changes in medication
If you havenât experienced any of these in the 60-180 days prior to policy purchase, you donât have a pre-existing medical condition per travel insurance.
For example, if you have high blood pressure and your medication dosage hasnât changed in years, it would not be considered a pre-existing condition.