Do not know whether someone else observe it or not but today I found my profile Gravatar changed. It is now different than earlier I have. Is it because today I have updated my profile information?
My previous gravatar looks like:
If you know you aren't using a picture uploaded to gravatar use the identicon. The picture changing popup actually checks if you uploaded a picture to gravatar for you current email address, and hides the option if it doesn't find one. The identicon option is safer since it uses different values to generate the gravatar hash, thus helping to disguise your email address from an attacker wanting to retrieve it from the hash, like described in Is using Gravatar a security risk? This is the default option used for new users. Unfortunately you've created your account before this change was made, so you still have the gravatar option enabled, but don't see it when you want to change you profile picture (no gravatar account).
Since you are posting a screenshot showing your email address you clearly aren't concerned with disguising it from potential attackers.
I found the reason, I updated the email in profile and it again get changed, so changing the email in profile has impact on Gravatar but I think, the only login email ID should have impact on these images.
reverted to old gravatar here:
and new one is here with different email Id: