Dad doesn't buy cheeses and Mom asked a nonsense question

My Dad's one of those people who would "never buy anything even for himself"  in other words he's a cheap stake.  Due to my country/province's dairy products being expensive  Mom or i have to buy cheese bricks/blocks when they go mildly on sale.  Because there's no point in ever asking Dad to buy cheese anymore for over 2 years.   

I'm going to be on my last block of "spicy cheese" (ie: Monterey jack, and Mexican Festival) in the next couple of days (no more in the Fridge only Mom's bricks/blocks.  So when Dad and I happened to end up at the most local grocery store ("Fresh") in our town,  I wanted to check to see if the spicy cheese was on sale (it was).     

I got home after doing the grocery shopping with the local grocery store (not a planned part of the shopping today) and I told Mom about the Fresh store having the cheese on sale.  She asked me if I brought any.  I reminded her I was with Dad, and when I'm w/ him,  he wouldn't let me buy such stuff vs if I was by myself like if I had stopped in there on my way home from work yesterday I could have brought some.

Later  before  I had my fruit and Mom has her lunch-  I asked Dad a hypothetical question of "If I was with him and cheese blocks were on sale at "Fresh" would I be able to buy them?"  And we had a huge fight about it the same fight which is why I didn't bother to bring it to his **** attention at "Fresh" in the first place.   Like he doubts it was actually even "on sale" despite what a sign says because sometimes the signs can be giant rip-offs.   Mom then asked me why i had bothered asking Dad then (about the cheese blocks when Mom can get them on Weekend-probably Sunday) -

I just wanted to know for future reference.     And also why the *** did Mom ask me if I brought any when she knew I was with Dad in the first place?!!