Normal rules for early distribution applies.  Unless your client was disabled or the distribution was used for allowable medical expenses, among a few other exceptions, the distribution will be subject to the 10% penalty.

The 1099-R should report NUA in Box 6.  Since you haven't seen the 1099-R apparently, did you figured the NUA from the historical statements?

If NUA treatment is to be applied in a lump sum distribution (provided all the conditions under §402(e)(4) and its regulations are satisfied), the 10% penalty would only apply to the pre-tax cost basis.