That's super interesting Denise and a wonderful curiosity. My mom, also in her 70s, tends to do what you're describing too. Even I do sometimes (in my 30s).

Sometimes when Mom and I are chatting but also thinking we'll speak in fragmented sentences.

As if partly speaking aloud what we hear in our heads while the rest of the content stays in ou heads. Although she does it more often ;-)

It sure will be interesting to see what researchers learn next about inner speech. Thank you for sharing your experiences! I appreciate you!