I am having headaches after my bilateral l4/5, l5/s1 lumbar facet medial branch block. is this normal.

Wait and watch: Typically no reason to have headaches after mediial branch block . Potentially may happen IF the needle accidentally went too deep and caused spinal fluid leak but still the headache in that case would be constant with some change with position ( lying down versus sitting up) . Alternatively could be from steroids if used for block . Best to ask the office that did the block.