Guinea pigs not eating alot of hay

Hi ladies, i adopted 2 baby guinea pigs (2 months old) about 3 days ago and am concerned as i noticed that they are not eatin alot of hay. They eat everything else-veggies,water,pellets, treats- but are not consumin alot of hay. I currently have the hay in a hay bag ontop of the litter tray and thought this would be easier for them to eat out of but am unsure if that is causing them not to eat alot. Do you have any suggestions?