Honestly, it sounds like you're worrying about something that isn't going to make a difference.
If you truly just view a photo on FB then no, of course it's not going to affect your reboot. If you are seeking out the material and / or fixating on the imagery on a regular basis then it's likely you've found a porn sub or a process that mimicks porn in ways and yes that is going to slow down your ability to heal your mind.
Also, when you refer to "Restarting your reboot".... what do you mean? The behavior is to quit using porn so there's no re-starting unless you've relapsed in which case you are restarting your quest to never use porn again. If you view the imagery in a pop up ad but dismiss the ad without fixating on it (or masturbating to it) then you are exercising the control needed to refrain from using porn.
No side effects of an image popping up and you dismissing it. But don't lie to yourself.. Don't seek out the images and don't allow yourself to focus on them. To beat this you are going to have to exercise self control.