The question is considered whether quantum effects associated with the electron recoil on the field quantization have any significant effect on the FEL operation in the X-ray regime. The gain formulae, spontaneous emission and electron multirecoil effect are considered due to spontaneous multiphoton emission. It is concluded that quantum effects are usually negligible in the x-ray regime above 1A wavelength. They only may be detectable in a stimulated Compton FEL if high enough gain could ever be realized.