It's been that way for as long as I can remember. We are talking about the same Parliament that chanted "Four More Years!" for Obama in 2016. It's also a intelligent move. Making the leader of the World's most powerful nation, and our largest trading partner feel welcome is just common sense.
It doesn't matter how long its been going on. In fact, that makes it worse. You can make them feel welcome without taking a submissive position and licking their boots, especially when it would not be reciprocated in the same way when we go visit them. Congress would not give 2 sh!ts about our visit and I doubt would be bringing their wives and former POTUS's to watch Trudeau speak, if they would even want our PM to speak in Congress. The entire Canadian political establishment were giddy, it was embarrassing.
We buy a ton of products and services from the US, you can't ask for no better neighbour, we can appreciate them as great ally, but we don't owe them anything, and we might want to keep some self-respect.