I think marginally if you view having the referendum in the first place as a mistake, given that it wasnt her mistake.
I think the argument that the country should be led by a Brexiter made some sense but the fact there are none to be seen speaks volumes and validates her position. If Cameron has stayed on all the Brexiters would still be buzzing around him strengthening their positions without having to take any responsibility for the mess.
(I am really looking forward to being able to turn that phrase "the mess Labour left us with" round onto the Tories now. From here on in the mess being dealt with is not anything left over from Labour.)