It could also have to do with residual stiffness/muscle soreness, whether it’s from yoga or doing other things in your daily life. Or just not having the mental focus that you did during your previous class – letting distractions get to you.
But I think just keeping in mind that progress rarely goes in a straight line is important. The more you expect yourself to do just as well or better than you did the time before, the harder it is do to so. I’ve noticed on occasion that I sometimes have breakthroughs in poses when I’m tired and expect nothing of myself – it helps me relax into a pose in a way I hadn’t previously (where I was apparently fighting myself and creating unnecessary tightness.)
