I do think that needs to be rectified in one of two ways:
1.) Make the bloodstain outside the boiler room much more apparent. As is, it blends into the environment too well, and you don't have access to the Detective View feature in 3D walking sections.
2.) If you finish investigating the four storage rooms before finding the bloodstain outside the boiler room, instead of telling you to go upstairs, Eva should tell you to investigate the hallway again, and if you talk to her, she should have a new set of dialogue where she directs the player to look at the blood on the floor.