The warning you receive about claiming your Medical Expenses is designed to bring it to your attention that your claim does exceed 3% of your Net Income. This does not mean you will be audited, it just means that CRA quite often requires the taxpayer to submit documentation to support their claim for Medical Expenses.
This FAQ link from TurboTax explains in greater detail how your income affects your Medical Expense claim: How does my income affect how much I can deduct for medical expenses?
You can rest assured that TurboTax is performing the correct calculations for this credit and is advising you that you may want to double-check your entries to ensure you have not made any incorrect entries.