Doubts on backbiting

Asalamualaikum, I am having really bad doubts if what i have done is backbiting or not. Recently, I have been thinking repeatedly if anything I am doing is backbiting. I got a tissue and was blowing my nose, some of the mucus went onto my finger. I then thought to lick my finger but I also thought that I would be backbiting on somebody while doing so. I then licked my finger anyway (I am pretty sure my intention was to backbite). After that, the person I was thinking if I was backbiting on them came. Please inform me if this would still be backbiting and I would have to apologise to them.