How can I tell if my email has been hacked?

Other than the obvious like family and friends saying they received strange emails from me

I use a yahoo email account ( I guess that us a web based email?)
So given this whole SSL thing, I decided to change my email password
Now I rarely if ever these days access my email via a PC. I use my iPhone to access my yahoo mail account. About two months ago I had changed my pass word gr no specific reason. I did the password change by accessing my account via the PC
Ok so hearing that yahoo has patched their SSL issue, last night I thought it prudent to change my email password
Ok so I log into my email and then hit account settings. It takes me to a page that says you have successfully changed your password. Only thing is that I had not yet made my reset paswird change.
So then from there I go to account settings and change my password . I create a new password and then get the you have successfully changed your password page.
So not comfortable with what all happened I go back in an hour later and create a newer password
But my concern is why when I logged in initially with current password, did it say I successfully changed my password?
Which leads me to concerns was my account hacked? And then what are some less obvious signs if a hacked email?