I have two Abyssinians. Sunny (male) has dry skin and sheds almost constantly. His fur tends to be quite course, I'm not sure if that's from his skin condition or if he it's just his natural texture. His skin improved a little after I got him neutered, so I put that down to hormone changes.
Lola is still a 'baby' so she has only recently gotten her proper adult coat so she has been shedding quite a bit. Saying that, she still doesn't shed as much as Sunny.
I know it's not diet related with my guys because when I bought them (no guinea pigs available for adoption where I live) and introduced them to a fresh fruit/veg diet, their coats went from dull and bristly to shiny and silky within a couple of weeks.
So long as the molting is even all over and not in patches, and Gizmo isn't scratching excessively, I think it could be ok. If you're worried though pop in to your vet to get them checked out.