Illustrator text alignment issue after export to pdf

Hello, I have a "mysterious" issue with text alignment in an Illustrator file. It's a document with various text boxes (end credits for a movie, that i import to After Effects for rolling), they are left / right justified, and are aligned on top - in my open document. As soon as i export a pdf, or just look at the document with mac's preview function - a few lines jump out of alignment. It also imports that way into After Effects. its not a regular jump in the alignment - it concerns a few lines, while others stay in the right position - in the SAME textbox. any ideas what could cause this would be highly appreciated, thanks in advance!