My wireless mouse suddenly became less responsive to my mousepad?

I was playing Minecraft a little while ago and my mouse pointer suddenly became jerky and laggy. I recently changed the batteries so I knew that couldn't be the issue and I tried plugging the mouse receiver thing into another USB port and still the same issue. I then removed the rubber mouse pad and suddenly my mouse pointer moves fluidly again. Why did it suddenly do this? The mouse pad is not dirty and it was working fine until a little while ago.

Could be it was blocking the laser…

You don't absolutely, need a mousepad, just the desktop, will suffice.

It seems that can happen with optical mice, at least it did for me. One of the mice I use has taken a dislike for one of my mouse mats but works fine with the other. The other mouse works fine with anything. I don't know why, there's no logical reason, but there you are.

I take it you did fit good batteries, the right way round. How does the mouse work just with the desk/table top?