You could check whether what you're seeing a second line at ~490nm or the actual IR with scotopic vision. You just need a diffraction grating and a cheap camera (to avoid frying your eyes).
My guesses would've been random interaction with whatever the beam is hitting to get blue, but yes IR is picked up more by the rods than the cones, which makes it possible to see it as a faded gray color rather than red. Try and make the room you're in as dark as possible