Should I permanently forsake Perl for where my abilities seem to lie?
If that's the only question that puzzles you - then of course not, but that isn't the decision you have to deal with, I guess.
Your abilities don't lie in PHP coding - they lie in what enables you to pass such a test with the kind of success you are reporting. But that's but a subset of your abilities.
In your situation I'd rather ask myself: Is that the kind of job I want to spend (part of) my lifetime in? Will I be happy cranking out PHP code? Is there enough nourishment for my hunger of knowledge and skill? Is the team ok, do I fit, do they fit my personality? And last but not least: can I adopt the business goals of the workshop?
If you can answer all of the above positively - then go for it, why not give it a try. There are plenty opportunities for perl wizardry in a PHP shop, and you can carry on coding perl as a hobby. The Monastery won't cross you because you "changed sides". There's no such thing as sides in language wars here with us (at least that's what I know from the Monasterians which aren't wont to troll for bites).