The loading.xcd figure calculated by Sorption module using Fixed Pressure task

Hi, everyone:
   When calculating adsorption by Sorption module using Fixed Pressure task, there is a result named loading.xcd document. It is shown that there is a  not very smoothly line at the beginning of the figure no matter how larger equilibration steps  are chosen. In my opinion, it should be smoothly during the whole line when system  equilibrium is reached. Is there anyone can tell me that why a not gentle curve existing and whether it is rational?
Thank you!