This is a common problem with the X-Trail. The driver's door actuator has a faulty seal, many Nissan dealerships have acknowledged that fact. Nissan Canada says they haven't had enough complaints to issue a recall or a service bulletin for that matter.
I live in Vancouver, my door was frozen shut for 3 days this winter, other than that it's been fine. My guess is many others have had a similar experience but didn't bother complain to Nissan. If everyone had I'm sure we'd have a better chance of seeing action from nissan.
Next time you see an xtrail driver in a parking lot as them if they've had a frozen door. It's funny some of the stories you'll hear. So far I've asked 5 people and all 5 have had problems. Only one of them has had it fixed.
Other posters have commented that their dealership has replaced the actuator free of charge, even off warranty. Others like myself have had no such luck. My local dealership wants $400 to replace it. I have opted to not have the actuator replaced at this time. If we get more people on this list I will contact Nissan again. It would be nice to see them held accountable for the cars they build.
It's funny, I love my X-trail, but when people ask me about it all they hear is the trouble i've had trying to get Nissan to fix my door.