Hi there
I too have the same as you, but just had strep throat and being treated with antibiotics, hoped that this would clear it all, but the redness at sides of soft palate still there, All the blood vessels in my soft palate seem to stand out and the remainder of my mouth seems pale. Look forward to hearing your outcome.
Rightly so when you hear the word biopsy. It sounds like you are in very capable hands and if the doctor who actually sees the areas is not concerned then I think you will be fine.Either one of the things that you mentioned could be the cause of redness.