General Just Normal Itching?

[BestGuineaPigs]

Today, my mom got my guinea pig, Ace out for lap time, and we found a damp spot on his back where his fur was sticking out. It looked like he had just itched that spot. Is this normal? We have had him for about two months and I have never seen this. Is this normal? Or should I watch him just in case?

 

[BestGuineaPigs]

Also, we pet it down, and he was fine.