Driver side door stuck shut?

[Lesjordans]

Has anyone else had this problem? for the past 2 days ive driven to the train station, tried to get out as normal and the door handle feels as if it isnt catching to unlock the door - results in me having to climb out the passenger side. Can cold weather cause this? Its been -4oC here the past 2 days, but its weird how the passenger door is fine. The door opens okay from the outside and tonight when I got home it managed to open fine. Just dont want to get stuck in if the passenger side door is frozen shut!