Understanding time constant of high pass filter at op amp input
You don't say what your error tolerance is, or what kind of accuracy or precision you need.  With 1% tolerance resistors, your output accuracy is limited to less than 7 bits of resolution.  So the question is, in the 4 Hz condition, does the rolloff error (caused my non-flatness of the response curve) at almost four octaves above the cutoff frequency contribute more than or less than 1% to the output.  IOW, is it a significant error source.

Calculate the capacitor impedance at 60 Hz, use that to calculate the R-C network signal attenuation in percent, and convert that to dB if needed.  For the real world, do the calculations for the worst case values at the extremes of the resistor and capacitor tolerances.