I just checked my 42 year old Blackhawk and it has the same tiny amount of play regardless if the hammer is cocked or fully down. No difference in cylinder wiggle.
As long as it locks up tight when cocked, I would think that is all that matters.
Call Ruger. They can tell you if it is OK and fix it if it is not.
Certified Glock Armorer, GSSF,NRA, Georgia Carry.Org, IDPA/Safety Officer