The stems of my mushrooms are bluish-greenish. Is it contamination?

Sometimes, we all get confused with bruised mycelium or green mold. Here is a good method to help you identify.
Grab a clean Q tip or cotton piece, soak it with some H₂O₂ or water and rub lightly the possible infected area. If it is a contamination, the mold spores will get attached to the piece, if nothing comes off then it should be bruising which is normal.