Preterite vs Imperfect

Hola Eugene

In this case, the narrator is telling us about their experience during "yesterday" - they are saying what was happening during the day. It's not seen as actions that had an end, it is in this case more descriptive. 

The narrator could have also used the preterite if their perspective is different, i.e seeing all these actions as things that happened yesterday and now it's the present, so all that happened had an end. But you can also "describe" your day explaining (with the imperfect) what "was happening".

I hope this clarified it. 

Saludos cordiales.

Inma