Actually I watched a lumbar puncture, and the needle hub was plastic that he used (the one in the LP tray was metal but he doesn't like to use that larger needle) And generally my tubes see alot of cleaning, mostly just alcohol swabs, but after the juicy patients, I use Caviwipes.
Besides it doesn't sound like they were pushing meds into the bag, but a port on the IV tubing (maybe the lock, maybe not) And depending on how long that IV has been running who knows, there could be blood in there, maybe there was blood on the outside of the tubing from a messy start, if they are reusing needles, do you think they take the time to use an alcohol swab to clean the port before injection?