No, it was actually Harper getting them down in Quebec during the election that began the strategic vote for Liberals into widespread support.
The NDP and Liberals were almost interchangeable to most voters and were deadlocked in support.
Once Mulcair became the most vocal against Harper's ridiculous niqab ban, he actually lost some support because the xenophobes in Quebec started to fall for Harper's desperate identity politics.
The rest of Canada rightly recognised this meant they would need to strategically vote for the Liberals and Trudeau capitalised on this by making campaign proposals based on economic stimulus, climate change and otherwise typically NDP initiatives.
That sent his support through the roof at the NDP's expense.
In other words:
He was ready, and he brought his pants.