This is not an indication of a security issue such as a virus or attack.
It could be something as simple as a run away script or learning how to better use E-utilities, for more efficient work such that your work does not impact the ability of other researchers to also use our site.
And while everyone is at risk, seniors can be a major target.
Remember that when you give out your number, unless it is an unlisted number, you are giving out your address as well.
People can easily do a reverse look-up on a phone number and see where you live.
They had quietly rolled this out a bit ago, but I only noticed then because I monitor and participate in a couple of Skype public chats that focus on new releases/features of Skype and development issues.
There does, though, seem to be a continuing puzzle around discrepancies regarding the actual limits.