Perhaps you, like I, have had someone say something like 'I lied' when what they have done instead is to have made a mistake.

This is sloppy language at its best. 

In order for a statement to be a lie, the person making it must know or believe that it is untrue.

It is still a lie if the person thinks it is untrue, but it really is true.

Lying is all about intention.

'Oh! What a tangled web we weave

when once we practice to deceive.'