no it's not. It's called looking after your partner. If you are my partner, and you didn't tell me, than I am going to request another partner, and make sure everyone knows that you are not looking out for your partners. It's a small world, and it would ruin your reputation.
Plus, how pissed would you be if you had a senior moment, forgot to put your gloves, on, and your partner knew this person had something and didn't give you the heads up?
You need to tell the hospital staff in your report as well. And if you mention it to the staff who is treating the patient, that's ok too.
Do your best to assess the patient, treat all patients like they are super contagious, and try not to broadcast PHI to the public if it's possible. But you need to ask them if they have any communicable or non-communicable diseases, it's part of your assessment.