Back in a previous chapter, I mentioned hat Chase is allergic to Servo, and you are all probably wondering how that is possible. Now, as for the topic of pets has appeared in a certain episode, we shall shine light onto the subject.
Servo is covered in a thin sheet of some certain substance, kind of like when dogs have their fur and it gets on your hand. That stuff that Servo is covered in doesn't suit well to Chase's frame and leaves it rougher than it should because Chase's body is more sensitive.
This substance means no harm, but it is actually only bots who tend to notice its presence. Humans don't actually notice the substance that is there, and no harm is caused to them if by chance they touch Servo.
The bots did explain this at one point, but honestly, no one seems to get it still how Chase could be allergic to Servo despite being told ten times.