Can any Sythe mods help me out here?

I got back home today and someone messaged me on Skype asking about a PM I had sent him on Sythe, I had never PM'd him before but he sent me a screenshot showing a series of PM's that had been sent from my account. Is it possible for a Sythe mod to check my account activity? I am very confused and I wanna know if anyone was on my account or if its a misunderstanding.

I have now also added two step verification to my account