Two hybrids in 13 years purchased new and didn't do this on either one. Never an issue, no leaks.
Seasoning was more of a thing with real canvas (not vinyl covered), things like canvas tents, older pop-ups without the vinyl covering. And it was for more than seams, it was for the canvas as well.
2013 Jayco Jayfeather X20 E, 2008 GMC Sierra 1500 Crew Cab Z71 SLE