The more proficient you become in the elements of shooting, the stronger you become. It is basic physics, the further you draw the bow, the more energy you place in the limbs to be transfered to the string, and ultimately to the arrow.
Many of us colapse once we reach anchor, you have, correctly I might add, found the importance of back tension which allows you to release from your selected anchor point. Many of us reach it, creep, and then release. Sometimes shooting as much as two inches shorter then the original anchor point. Depending on the energy storage of the bow, that will me as much as five to six pound loss of draw weight.
No sir, it is not your imagination....Kudos to you Sir.