I think she was just recounting what she saw, and that event struck her as being strange.
Because of what Andy was told in regards to Suzanne texting her friend that day, I think Suzanne was still alive at that point (up until 12:30 at least).
Something had Barry stressed and worried, and I think it had to do with some sort of conflict between he and Suzanne.
I think the line about going home and making “the wife happy,” shows that all was not well. I think he went home, they argued, and he killed her.
Of course it’s also possible that he had already decided to kill her while he was still at the job site, and that’s what was on his mind.