Realtor told the appraiser about backup offers- ethical?

[Henley H.]

Our real estate agent mentioned to the appraiser (prior to the appraisal) that their was a backup offer 'well above asking'.  She also mentioned that there had been a number of offers that exceeded asking price.

She has mentioned this a few times to me now in an effort to show she did her part to make sure the property appraised, however, I feel it borders on unethical.  I thought the point of an appraisal was supposed to be completed by an independent, third party and she is muddying the waters by sharing information about other offers.  

As the buyer who requires financing, I appreciate that in certain respects it is in my best interest if it appraises at asking, but I would also like an accurate figure that is not influenced.

Is it customary or legitimate for a realtor to share information about other offers with the appraiser prior to appraisal?