Spring trap + Multicaster interaction

Hi,
I was wondering, so the wording on the card from Spring trap say’s Cast a secret from your deck. lets say we use it and hon kill and cast a explossive trap (fire spell school) and freezing or ice trap (frost). then the card of Multicaster say’s draw a card for every spell school you’ve cast that. now if we play Multicaster after we used spring trap it won’t count as 2 diffrent spell schools. is this a bug or intended, same applies to secrets cast through rinling’s Riffle.

Multicaster says “each different spell school you’ve cast”. Those secrets weren’t cast by you, they were cast by Spring the Trap (or by Rinling’s Rifle).