Can I be disciplined in work by posting on twitter?

[Louise]

I work in a small petrol station shop on a 10 hour contract part time while I study at uni. About a week ago, one of the staff tweeted me asking if I had the weeks rota which I unknowingly tweeted back.

I've just received a phone call from a member of management saying its come to their attention that I've posted private info about the shop publicly for everyone to see and that it's a huge breach of security as it also showed the rota for the managers. I deleted it straight away but she said I may face a disciplinary for it and I'll be spoken to about it.

Can I be disciplined for something that was a genuine mistake? I honestly didn't realise it would cause any kind of trouble when I tweeted it. I see now that it could've been a security breach in a way but the only people who could see it are my friends?