Possible problem with kit lens

[Verbium]

My trusty 18-55mm Nikon AF-S lens is causing me some problems, went on a photography trip to London a few weeks ago when it was below zero temperatures and after a few hours it started to become very sluggish on the zoom. By the end of the day it was almost stuck going past 40mm and i assumed my lens was freezing in the cold weather.

Thought it might have been normal but took the camera out today and it was still pretty sticky and I'm a bit worried the cold snap has killed my lens. Suggestions? Would this be covered under my warranty?

 

[Verbium]

Sorry i'll clarify a bit more, when i'm changing the zoom it sticks a lot more than it used to. It doesn't feel as fluid and natural anymore.

 

[Verbium]

Got it with the camera in August of last year, its been pretty smooth up until London, it does get a far bit of use though.

I'll keep using it in other weather conditions to see if it makes a difference. Thanks for the advice.