Probably not an accident that these two things have coincided...
There was a Nanos tracking poll graph on the CTV website last night showing Liberal numbers tracking up in Quebec over the last four nights, with the surge said to be concentrated in the Montreal area. From April 6th through the 10th you see the bump upwards. This was Ignatieff speaking in Brossard on the night of April 6th:
The Pont Champlain has become an issue in the Montreal region in the last few weeks with the release of those engineering reports on its status to La Presse a few weeks back. Ignatieff has stepped out in front with a simple, clear promise here. The way it is framed is notable too. A "bridge for Canada" has a strong federalist appeal to it that would resonate in Montreal. It's also a good one on another level, the "rassembleur" method of politics that Ignatieff describes as his preference is here too, building bridges, a good metaphor for it.
Now if it's not this promise that's causing the bump, it's possible it's just the campaign itself and the platform policies that are doing it. At the rally held in Scarborough on Saturday there was a national unity pitch made, federalists in the Montreal region may be firming up based on such appeals as well.
And of course, we have to watch to see if this bump will bear up over time and in other polls. For now, it looks like the bridge promise, that may have been overlooked last week while other issues flared up, may have made an impact.