While there was nothing wrong in you filling in at the request of the priest, this shows how disorganized that Mass was. No one should have to “do in a pinch”. It seems that it was a regular weekday Mass, so there should be a roster of people to read on specific days. Why would there be no guarantee that a reader would show? People need to make commitments. Wouldn’t there be people that regularly come to the Mass? Even if some only come to Mass there on one specific day per week, they could make a commitment to read once per month.
What’s wrong with being the reader “in a pinch”? Well, you are not properly prepared. If you are an experienced reader (as I am), you will be able to do a quick look over of the reading and probably do the reading well. But, an inexperienced reader may not do very well.
All people who will read at Mass should be trained prior to the first time they read. This can take quite a long time if done properly, as it could need to include aspects of elocution - enunciation, pronunciation, breathing, emphasis, pauses, etc., which most people have never been exposed to. Most people also need to be taught how to properly use the microphone, or, where the church / chapel is small and there is no microphone, how to speak so that all will clearly hear what they are saying.
This is why I see the organization of that Mass to be disorganized. Someone (not necessarily the priest) should have recruited and trained a number of regular Mass-goers to be rostered on a regular basis to do the readings and not have priest needing to resort to recruiting someone immediately before Mass.
