I am pretty sure that I had an associated Meta account in Stack Exchange already and I have also asked a question. (Though it was marked duplicate and I am not able to search for that question anymore. Maybe it was deleted too?)
But today, when I came here, it asked me to sign-up again and re-associate with my account.
Was my account deleted for some reason in Meta? I don't see any reason if so, because all other Stack Exchange sites are perfectly fine.
The per-site meta accounts are not deleted separately from main accounts. The MSE account can be deleted by request of it's owner (unless it's a spammy account of course, then employes nuke it).
You've mistaken Meta Stack Overflow with Meta Stack Exchange, because there's the duplicate question you're talking about:
Can SO add line numbers for any code posted in question
And it is on the Meta Stack Overflow, correctly assigned to your MSO profile.
Not sure, but is it possible that was before the MSO/MSE split? (See Operation 'Split, All The Metas!' Shall Commence On April 16, 2014)
If so, it might be that accounts that only had activity on MSO and not on MSE were not recreated as MSE.
I can't find any users in the list matching your user name, so it seems you didn't have an account here yet. (maybe you are mistaking with another meta?)
Also read: When will inactive accounts be deleted?
It is well possible you are matching the criteria:
The user has not visited the site in six months
AND
The user has only 1 reputation (i.e. has never received an upvote)
