Silver Plating - weird residue marks??

Hi everyone! :)
I'm pretty much still a jewellery newbie, so apologies if my questions seem a bit silly.

I took some brass work to be silver plated and got it back yesterday from the platers - only to notice when i got home that on my shiny plating some strange little residue marks left on it.
I know the platers were very busy, and were rushing to finish my work when i got there so i think on a normal occassion they would have got this off before giving it back to me (I've had silver plating done a few times now and never seen this before!).
I also know the marks weren't on there when before the plating!

Hmmmm.. anyone know what the marks might be and/or how to get them off without damaging the plating? they almost look like water marks/like when you put a sticker on something and peel it off and it leaves behind a residue (but its not sticky at all!)

I got some gold plating done too at the same time, and there were no weird marks left on that!

Thank you so much in advance if you can help!
:)

I think you would be well advised to take it back, because the plater will be familiar with this problem and just maybe hoped you would not notice. The only self help I might try (rather gingerly) is to use a new clean silver polishing cloth. Dennis.

Thanks Dennis! yess i definitely will contact the platers, fingers crossed they have some kind of idea of what it is, but you're probably right that they noticed it already but didnt mention it! Sometimes i do get a little worried because i'm clearly a newbie to all this, that people doo try to fool me a bit and hope i wont notice haha! Good idea with the new cloth, will try that too! Thanks again :)