Leak under kitchen tiles?

EDit

Hi all, looking for advice. Been living in house for ~10 years and have not touched the tiled kitchen floor in all that time. Anyway, over the last few days, we have noticed a single tile that is very warm (the tiles around it are pretty much the same "cool to the touch" temp as all the others in the room). Reading up on the web suggests this is a likely caused by a leak in a pipe running under the kitchen, so I am primed to give a plumber a call. However, thought I'd check here to see if there is any other possibility before getting out my chequebook.
Thanks

K.Flyer

One of the first possible tell tale signs of a leak under a tile is the grout around the tile and the adjacent tiles starts to go a much darker colour than the rest.
It may be that a pipe is higher in the concrete than it should be, but one single tile getting warm would be unusual.

sky6

You could also try a Moisture Meter over the grout.

I had a similar problem in our kitchen after we moved in everything was then then all of a sudden a wet spot in middle of kitchen. I had to lift tiles and found a joint although connected was never tightened. Luckily we had a few spare tiles and was able to repair back to new.

EDit

Thanks for replies. Unfortunately, the grout is black, so hard to tell from colour alone. We have someone coming out tomorrow to have a look so we will ask re: using a moisture meter