When I first started yoga 4 years ago, I couldn't bend in a forward fold properly or touch my toes while sitting down. I've gradually increased my flexibility, but for at least the first year, my hamstrings would feel sore the next day almost every time. It felt like DOMS (delayed onset muscle soreness) to me, so I figured I was building up strength. But I haven't heard anyone else mentioning this, so is it possible the soreness is from overstretching?
Anyway, I mention this because due to flu sickness and the holidays, my yoga practice has taken a short break. Recently, I went back to a full 1.5 hour class and went through the primary series. The next day, my hamstrings are sore again, but mildly. At the same time, my shoulders and upper back were also sore, so I knew I did a lot my body isn't used to.
So, is this normal? Am I pushing myself too hard?