hairline cracks behind woodburner stove

[littlesaxos]

Hi there.
I have a free standing log burning stove in my conservatory I have noticed that hairline crack has appeared behind the stove in the plasterwork.
The builder who plastered the wall behind the stove assures me that "heat resistant plaster" was used but I have my doubts about this.
Is there any way I can check that heat resistant plaster was used.
Also what would you recommend to repair the hairline crack in the plasterwork?

Thanks

 

[flynnyman]

Any pics?

 

[trialsbiker42]

How soon was the fire on after it was plastered? When I put my woodburner in it took the skim off the render like an eggshell off a boiled egg, I ended up tiling behind it instead. If it doesn't sound hollow when you tap it then you can just easyfill the crack. If it does sound hollow then I'm afraid it will end up coming off.