Both the PLSS and the RCU can flop around a lot. When we first rigged up the suits, I was surprised. So yes, we know the astronauts had to lean in order to accommodate the eccentric position of the PLSS.
There is also possibly a physiological explanation. One of the effects of diminished gravity, as the crews reported, is diminished balance. Equilibrium, it turns out, is fairly highly attuned to rotation rates evolved in Earth gravity. And you don't topple fast enough in lunar gravity to trigger an uprighting reflex. This means "upright" on the Moon is a broader cone of roughly vertical angles.