Dead Pixels On 5D II

Just asking for advice,
I've been happily using my 5D Mark II since January.

Recently I've been doing some long exposure shots at ISO 100 (autumn creeks and the like) and noticed LOADS of dead pixels.

They're different colours, some white, some red, some cyan.

There are probably at least 12 visible on each image, particularly in flat areas of colour.

I know the odd dead pixel is inevitable but never seen this many on a photo with any camera.

Is this within normal limits do you think? Or should I ge sorted whilst under warranty?

Thanks