I had about four flights where I didn't get pre-check. This was around the time that I noticed that the first and middle names were separated by a space in the first name field. I called DL and was told that the name in the security fields were correct (matching my ID and with first, middle and last) and that I shouldn't worry about it. I decided to let it go at this point.

I just took two flights where nothing had changed from above in my name fields but that I did get pre-check.

My hunch is that DL knows about the glitch in the names but they've adjusted so that it looks OK, matches the TSA files and doesn't mess up the pre-check. In other words, it just looks wrong to the psgr but looks alright to everyone else. Above all, I was able to complete the flights and go through pre-check as usual.