Unless you elected OUT of Bonus depreciation, I think it is doing it correctly.  The 6251 Instructions say:

"Don’t refigure depreciation for the AMT for the following ... Qualified property that is or was eligible for a special depreciation allowance if the depreciable basis of the property is the same for the AMT and the regular tax."

As a side note, even if the above didn't apply, the Recovery Period would still be the same (assuming it was not Section 1250 property and placed in service after 1998; but 150% DB would still apply).