Generally, no. Flexible benefits contributions are reported as non-taxable wages and income on your W-2. If the IRS audits you, you will need to show total expenses and receipts from your service provider(s). So keep a copy of your reimbursement request forms and receipts for your records.
However, it is important to note: Your benefits may become taxable wages reportable on your W-2 Form if you fail to timely substantiate (verify) a debit card transaction as a qualifying medical expense or use your debit card for ineligible expenses.