I didn't calculate, I guessed. Out of curiosity, I guessed your before picture at 26% body fat and calculated your LBM, put you at 162lbs. So, I whereas my 50-60 lbs was a gross exaggeration, without knowing the details of your before shots nobody will know for sure. Do you have body fat measurements written down by chance?
Even if my body fat estimate is roughly correct, that means you lost 58 pounds of fat, and gained 25 pounds of muscle in the same amount of time. Still, a fantastic accomplishment!
I'm glad you have such experience in the gym, but as far as I'm aware, muscle memory is a misnomer. Muscles do not have memory, though, I did read somewhere that if a muscle had grown to a certain size before, then subsequently shrank through atrophy, re-growing the muscle would occur in less time. Perhaps that's what you're referring to?