Bug with Twisted Fate and Thunderlord's mastery

i was playing tf with the thunderlord's decree mastery earlier and i picked a card and went to gold card. after i locked the card in, i auto attacked an enemy aatrox. thunderlord's proc'd, but my gold card did not, and it went off on the next auto attack couldn't recreate later in game (did several gold cards and a couple even hit with thunderlord) but i figured the bug should be reported