Can HER2 status be downgraded?!

I just received letter in the post from my consultation with breast surgeon when I was given my initial diagnosis (+++ grade 2 invasive cancer)

On the letter it says ‘positive HER2 protein however the pathologist advised repeating HER2 on excision specimen’

Maybe I’m being dumb but what do you guys think this means? I interpreted it as there may be a slight doubt that i am her2 positive and they want to double check?

I’ve had further biopsies and tests since the letter & follow up with oncology Saturday so will find out more then.

Just wondering - Has anyone ever had HER2 status go from + to -?! Is that even possible?