Originally Posted by Ripplinger
I had this same thing happen to me one day, I didn't have a crash though, the wider row height just appeared out of nowhere, and yes, it was annoying. I couldn't find any setting that controlled it through. Next time I rebooted and restarted Calibre though, rows were back to normal again. I still don't have a clue why it happened, I just chalked it up to some glitch.
Pretty much the same here.
Closed Calibre, then later turn it back on and the wider row height appeared. Same size text, but the row was twice as tall as it used to be. Checked to see if I'd bumped setting somewhere, but didn't find anything to change.
Closed it, opened it back up, and the rows were normal again.
Don't have any idea what triggered it.