Hi ima,
First of all congratulations on your new mattress. 
It also sounds like you were at the right place at the right time to find what you wanted in their clearance section and that is certainly great value.
Foam density has a very “loose” relationship with foam firmness or softness and any density of foam is generally available in a range of firmness levels. Different firmness levels can have a narrow range of density variations but they will generally be close to each other. My guess is that you have the everflex foam which is their best polyfoam and has a density range of 2.6 lbs to 3.2 lbs / cu. ft.
3.0 lb foam would generally be very high quality.
I think you did very well … and I appreciate the feedback and information as well about the ordering details or variances which can catch people by surprise and be a little annoying … even though in your case it certainly doesn’t change the fact that you received great value.
Phoenix