I'm not finished yet, but is this what you meant to say?

"I've no idea," Remus said. "He said it was because he found the train less stressful than flooing straight to Hogsmeade, which is obviously a line, but I can't think of any other explanation. After the Dementors came on board he Apparated away pretty quickly."


a line instead of 'a lie'? I wasn't sure, because 'a line' could make sense, but 'a lie' is generally the more common phrase used... so I thought I'd bring it to your attention.