If the pelvis can tilt due to a tightenin of tendons induced by HRT, then it stands perfectly to reason that it is, at least possible, for feet that continue to grow throughout our lives, due to loosening of tendons and ligaments, to retract to a smaller size as they tighten due to the effects of hormones.
I wouldn't be too quick to rule it out as impossible, even if it isn't experienced by everybody, or even very commonly.
Saz x