Superstore and memory problems!

Superstore is a big store in Canada which most people go there often to buy their groceries.
A bus is dedicated to the residence that I am living in on Sundays 1:20 PM. Also small number of days are exceptions ...

Last week Saturday!, 1:15 : I rushed through to not miss the bus. Meeting few people in the way, I realized that Sunday usually comes after Saturday!

Last week Sunday, 1:15 : We were only "three" people waiting downstairs for the bus. One of us guessed that today is the special date which the bus never comes!

Today, 1:15 : I was alone downstairs, so something was wrong ... After calling my friend, I realized that today is Saturday!