No, it's gaslighting. There is no requirement for gaslighting to be repeated or intended as abuse. It's also not about how blatant the lie is. The key criteria is that it has to be trying to convince someone that their own perception or memories were in fact not the case. Someone saying that they didn't eat the chocolate cake while still having chocolate on their mouth may be blatantly lying, but not necessarily gaslighting. Someone saying that they didn't eat the chocolate cake to someone who actually saw them do it with their own eyes, in an attempt to convince them that their own perception was false, is gaslighting.