Not necessarily. A change to gross income can ripple thru other areas. For instance, if you receive social security benefits, adding additional income can increase the taxable portion of social security (see lines 20a & 20b on 1040). Similarly, it can also result in a decrease to certain adjustments (lines 23-35 on 1040) if your income is in the phase-out range for those adjustments, which would then boost your AGI beyond the amount added to income.
To know for sure, you'll need to look at page one of the 1040 and look at specific figures, including those mentioned above.