I agree. It could just mean they want to tell you your results are negative. It sounds like a standard message to me.
Aj
No, I don't think it has anything to do with you being positive or not. The message that was left is probably standard - they do not want to give too much information in case somebody else is getting the message. Also, the fact that you got your results within a few days has nothing to do with whether or not your results are positive or negative. Try not to worry - you'll get your results soon enough.
Best,
Em