I think my student loans are in default. I called the Treasury Offset call center and they are not showing any offsets for me. Is my refund safe this year?

It is hard to say. If they are not showing an offsets in their system, then there isn't anything telling the IRS to with hold the refund and apply to past debts. I would keep calling the offset department every so often after you file to see if something does come up in their system (at least you would know then).