Jim,
About 6 months ago i found the EXACT same thing on my one nut. I couldnt remember if it had been there years and unchecked, or if it were something entirely new. It drove me mental and led to many sleepless nights.
Anyhow, finally got to see a Dr (dont have a family doctor here in Ontario- hooray ohip!) who sent me for an ultrasound.
It came back as an epileial cell cyst? Or something like that. And 100% not the C word.
Don't stress it, most are nothing, and the fact you found it while so tiny is even better. and just further proof that it's likely nothing. But go thru the motions and get it ultrasounded just to give you piece of mind. And like someone said, even if it we something needing attention, it's cure rate is like 95-99% and the 5-1% likely waited until they had a third nut before getting checked out.
From the sounds of it, same as what I had (and remains there).