Gyno is when you have glandular breast tissue growing behind your nipples. In the early stages (first few months) this will be soft and squishy. You should be able to feel these lumps. After a prolonged period, (6-12 months) these soft lumps will become hardened through a process called fibrosis. Once fibrosis happens and the lumps turn hard, surgery will be the only way to remove the glandular tissue. While it is still soft, you can still hope it will regress naturally (once the offending stimulant has been stopped - Finasteride in your case) or it may be reversed with medication. Ideally you would hope it regresses naturally as anti-estrogenic/SERM drugs are bad for hair and come with their own side effects.