Insomnia is a sure sign of withdrawal. With your nervous system suppressed by alcohol so long, it excites and fires off when the alcohol is removed. I would often be up for 4 days straight without a wink after a binge of a week or longer.
A more serious sign is shakiness in the hands and profuse sweating. That was always my sign to get a drink in me before the hallucinations began when I was drinking every day.
Monitor your symptoms and make a plan if things got worse.