The following sentence is from a dictionary:
No me había fijado en el escalón y casi me caigo.
I'm confused that the past perfect is combined with present tense. I'd expect simple past in the second part.
For comparison that's like saying "I hadn't noticed the step and almost fall", while I think that native English speakers would say "fell". (I'm not native English, though.)
I've already asked some natives speakers (Mexico and Cuba) and they both say the sentence sounds correct to them but they couldn't give me an explanation that sounded reasonably to me.
I'd like to understand why the sentence is correct. It's not according to anything a textbook would teach, where it reads that the use of past perfect requires a reference point of time in the past. I can also not see any of the textbook usages for the present tense here.
Note, while I use English grammar terms, I refer to the Spanish grammar. Though as far as I'm concerned the English and Spanish grammar are in accordance to the respective matter at hand.