You are right PSG has a weakness for English teams, I can also recall watching PSG vs Aston Villa 2nd leg match. In that game, PSG  struggled so badly to keep up with Aston Villa and later Lost to Aston Villa with a 2:3 defeat.

I believe English teams has their ways of suppressing PSG to some extend. I wasn't all that surprised when Chelsea defeated PSG in that Final because I already had that thought closely that Chelsea might defeat PSG and it happens, although initially I was too sure, yeah it was just a probability on my prediction based on PSG previous encounters with English clubs .

PSG defeats to Chelsea is not actually a big deal either. Chelsea is also a big team too and have won stronger opponents like PSG in the Pasts. Matches like this have been occuring in football where you will see a strong and well inform team been defeated by a lesser opponent.