Some people believe that because they are a professional that they are perfect! I always encourage my patients to question things or medications if they sense they are wrong - we are all human, we all make mistakes. We all have bad days, anyone that says different is kidding themselves. Most pharmacies have techs that fill the medications and then the pharmacist checks them. As a registered nurse, I really don't have anyone checking behind me, so having patients question procedures or medications is a welcome second check on bad days.
The other day I went to the orthopedic doctor for an injection - it was a new medication for me, so I was asking the tech questions about it before the doctor came in, well it was the wrong injection that he had for me. Thankfully I asked, not that it would have killed me, but not the plan we had put in place.
Bottom line - never be afraid to question anything! If someone is offended by the question, run don't walk out. Many a person have had wrong operations because they didn't verify what was going to happen.