[ne8il]

I had the same situation recently - a single German cockroach chilling on the front of our dishwasher. Being sufficiently terrified by reading r/whatisthisbug and the like, I had a pest control company out the next day to treat. They could find no signs of infestation and I haven't seen a single one since (and we did set out traps to monitor). The Orkin guy who came out said it's not uncommon for a lone individual to venture into a home.