"No Risk"
"Zero Risk"
Simply Forget about it and Move On. You did ot had any risk with respect to HIV.
HIV cannot be transferred from person-to-person by a cotton ball, no matter what. It can only be contracted by having unprotected, penetrative sex (anal or vaginal) or by sharing intravenous needles. Needles are not re-used in hospitals or clinics, so that is no worry - today, intravenous infection ONLY happens when IV drug users share needles.
There are no "what ifs" that you could add to this event that would make it a risk for HIV.