who made the threat on Canterlot in "A Canterlot wedding"

Okay this is going to sound like I'm randomly spit-balling late at night when I should be sleeping but hear me out. Remember A Canterlot wedding when they said there was a threat on Canterlot? We know that not even chrysalis is dumb enough to warn them days maybe weeks before her attack. So who warned the princess? unless the threat wasn't about the changeling attack. What if it was Tirek trying to psych them out? Or he just takes his humor from knowing that they knew about his attack maybe a year before it took place. Basically this is what I'm trying to say: Tirek made a threat on canterlot a YEAR before it happened to make Celestia and the ponies run around chasing their own tails and freak them out. It was dumb luck the wedding and thus the changeling attack happened at that time OR he warned them so HE could later take over

Please comment so we can all talk about it