My parents do this!!!
I can tell when they're just manufacturing something to argue about to get out whatever they're frustrated about with work, a hectic day, stress or whatever.
They also argue about when/what type of situations. Like what day last week did they make X for dinner. Does it REALLY matter if it was Tuesday or Wednesday??? NO! Of course not, but if one says to me, "Well last night your Father made a great steak on Tuesday" it's, "No, I made that on Wednesday." "No, it was Tuesday, I remember because it was after I picked up the prescription." "Right, and it was after I went to Costco - that was WEDNESDAY!"
UH, IT DOESN'T MATTER!!!