hello and welcome to HCM,
I do understand your concern regarding the swelling even after surgery but since the swelling is small then in all probability you have nothing to worry about.
However unless we do a biopsy
we can never be sure than the swelling is benign.
Biopsy is a safe procedure and since the swelling is quite palpable then the surgeon does not have to dig deeper or dissect deeper for the tissue to send for biopsy. So you do not have to worry about facial nerve
Get the biopsy done as soon as possible so that you can put your mind at ease.
take care and get back to me with the report if possible
Dr Sriram Nathan