Paypal Donate button adds an image?

[hitmann]

When I added a "donate" button on my site, there is a image showing in plain light grey at the right of the donate button (from https://www.paypal.com/en_GB/i/scr/pixel.gif).
I've never seen that before. Why is it showing?

 

[hitmann]

That's what it show:

http://i6.tinypic.com/157jh8k.gif

When i look at the source of the grey image, it shows https://www.paypal.com/en_GB/i/scr/pixel.gif

 

[hitmann]

not the kind of site i can post here i'm afraid.

but i've removed it now, just in case it's a it's not safe