Roof tiles "lifting"

I had a new roof put on a couple of years ago.

This week (perhaps due to the cold weather?), I noticed that one tile seems to have "lifted" say 1/2 inch. The rest of the roof is fine though.

It is the second row down from the top, and near my boiler ventilation.

Is this due to the weather / heat changes, or something more sinister?

Thanks

Dave

which tiles have you got? can you post a picture?

the tile has probably snapped under the tile above then the half you can see has fallen into the gap between the battons. The recent freeze could put extra force on any cracks caused by previous work. Replacement tile I think