Spacey Kindle Issues

In formatting for Kindle, uploading the manuscript on Kindle to see how it looked wasn't helpful. It went up with all these weird sentence breaks. So now I don't know if when I put it up on Amazon for download, if it will have these same weird line breaks. Frustration. The Amazon publishing guide didn't answer this issue. This book, Soul Mates, isn't even on of my favorite things I've written. I like it well enough but I wrote it on a dare and then kind of liked the story. It's more of a novella and I'm putting it up as an experiment so I'm trying not to obsess over this stuff. But I still want it to be perfect. Maybe its the Virgo in me. Then yesterday I downloaded a free preview of a book and it has the same weird line breaks. Like you're tolling along and suddenly in the middle of the sentence the words drop down on a different line. Why? Did this guy format the manuscript wrong? Was there some other conversion issue I'm missing here? Anyone else experience this issue?