Someone did something in Google+, but what did they do

google-plusnotifications

What actually happened when the Google+ notification says a contact "did something"?

Here's a screenshot of the notification I see in Gmail about G+ activity:

notifications drop down

Rahul yadav added you on Google+.
Gaurav Tripathi & Nilesh did something.

But what did the contacts on the second line actually do? Does this wording mean anything in particular?

Another example:

did something mention

Edit : Now, That notification is modified as follows.

New Modified Notification

I assume

"They did something = They added me into their circles"

Best Answer

I got this notification in GMail, while on Google Plus I got a notification those contacts added me back.

It is possibile that this is a new notification type previous versions of the notification counter didn't have support for, and thus "did something" is what they fall back onto.