I haven't lifted heavy with consistency in a few month, but the last few times I have done Romanian Deadlifts (Knees slightly flexed, back flat), I have felt this seriously tight sensation in my lower back at the bottom of the movement. I initially thought it was extreme tightness, mainly of my Quadratus Lumborum (QL), but I never had it the first 8 or so years of lifting, and at times much heavier weights than are casuing discomfort now.
From glancing at my form in a mirror, it seems that my low back is rounding a bit at the bottom of the movement, but I'm sure my form wasn't always perfect before, and never any discomfort.
Any ideas/experience with the same thing? I love this lift, but I don't want to damage my back.