That is an amount of contribution into a cafeteria plan (URC section 125) - your husband has an account in health care OR child care OR parking cafeteria plan.
That amount is excluded from box 1.
Let me know if you need help in reporting.
Some employers who do not offer employer sponsored health insurance - use section 125 health saving account to put pre-tax money through payroll deductions and use these funds to pay a premiums for employee's health insurance.
This technique allows to pay for health insurance with pre-tax money.
So you guess might be correct.
That is not taxable income because it was already excluded from box 1 - so you should not worry about reporting.