If you reconstitute with 5ml it'll be a lower concentration than 3ml for 40iu, so it somewhat reduces the risk, but if 60iu is sitting around reconstituted for a month that will make things worse. Unless the savings per iu was significant, I'd personally stick to lower iu vials so they get used more quickly.
I had an 18iu vial reconstituted, then went unused for 2 months because plans changed. Crystal clear. When I tried to filter it, 13mm filter completely seized up half way through.
After reconstituting a fresh vial from the same kit, it filtered just fine. That told be the "clear" vial was packed with subvisible aggregates. By the time you can see a microscopic "filament" aggregate with your naked eye, it consists of tens of millions of rHGH monomers stuck together.