Lateral Thinking Puzzles - third time is best!

Was there any sort of wordplay used in the text?
Or other type of joke or cleverness?
Did the text make a direct reference to music that might be played in church?
An indirect reference?
Did the text make a direct reference to the act of playing music in church?
No to all
An indirect reference?
Sort of?

Is this just in the context of the text saying the sender wouldn’t be at church, and there’s no further relevance to the question/answer?

If I’m reading that question correctly: That is not correct.

Is the reason why the sender wouldn’t be at church relevant? Was it mentioned in the text? Did the sender have any (relevant) medical conditions?

Was there a reference to your mother’s age? Is your mother’s age important?

Does your mother have a new responsibility because this person will not be at church?

Does it matter whether the sender physically typed the text or instead voiced it?

Does the specific date of the birthday matter?

Yes to all three.

No to all.

Was there any additional earlier information (ex: a different text about a change at the church, say a guest pianist coming) that you used to guess the identity of the texter?

Does it matter at all the reason the texter would not be at church?

No.

@Fretful_Porpentine just asked that, and yes.

We’re almost there.

Was it something similar to this:
The text said, “I can’t be at church because my lumbago is acting up something fierce, but happy birthday…” And you happened to remember before your mom did that Mrs. Whoever, the church pianist, sometimes complained about bouts of lumbago.

Not quite.

Is her medical condition vision-related? Did it affect her ability to text? To play the piano?

Was it based on a fact about the sender that you knew but your mother did not?

Is the medical condition hand related?

No.

Yes.
Care to solve it?

Is it Carpal Tunnel?

No, but not really relevant.

Remember, the ultimate question was “How did I know who it was?”.

Did she say that her hand injury was going to prevent her from attending church?

Yes, that’s it. She said in the text that she wouldn’t be at church because her tendonitis was acting up. But tendonitis isn’t ordinarily the sort of thing that would keep someone away from church… unless one’s reason for being at church was playing the piano. Ergo, the sender was the pianist.

I was on the totally wrong track on that one, I thought that the key would be how this random person knew it was your mother’s birthday.

Later this summer, my neighbors might catch me using my vibrator in the backyard. What am I up to?

True story, and I swear it’s innocent.