Nah, in my case it was repeated behavior. A month or two ago - I sent something her - left on read, than we did not chat. 2 weeks later has done the same - no reply again. Went NC for a month. Than we randomly met outside, she texted next day. Than a couple days later I initiated and we met and had some drinks, next day texted her, had a little conversation and this is where she left it on read. It happened last Thursday - no text ever since.
My gut tells me to move on and never initiate again considering the amount of BS I had with her. But at the same time I was thinking to ask her out next week for some action date like trampoline jumping and if she flakes - than it is 100% done.