I won't speculate on whether this kind of "mountain out of a molehill" storytelling is a common occurrence for your mother or just a one-off, but I will say that I have met a number of people in my life who did this kind of thing regularly.
My interpretation was that these people generally had pretty banal, inconsequential lives, and so this behavior was a way of injecting some significance and gravitas into what was otherwise a pretty boring day-to-day existence.
