Similar thing happened to me!  I did a Robocoin transaction.  When I sent BTC to the address provided by Robocoin, some spammer dumped a few satoshi on that same address.  Well, the Robocoin software wasn't expecting the extra deposits and totally blocked everything.  At least Chris who operates the machine is a total stand-up guy who gives kick-ass customer service fixed everything after a bit of working on it.  Now, the guys at Robocoin have fixed the glitch. 

But here is the real problem: these spammers need to be stopped.  The very next version has to have an anti satoshi feature which block stupid dust transactions to many addresses. 

I freaking hate spammers.