Sorry to post such an odd question, but my nerves got the better of me. I had a red bump checked out on my lip that I suspect was just an inflamed blackhead, but after reading a bit online my doctor did a PCR swab for HSV just to make sure. I noticed when they swabbed my lip the tip of the swab turned faintly red... and I later realized it was from my lips being stained from eating lunch earlier. (I had tomato sauce) I worried that maybe that would effect the test... is that possible? Again I know it's a strange question but I want to know if everything is ok.