This just happened to me too last night. I didn't see it ever saying it was available but only I think because I stopped using that computer early enough yesterday evening (in the UK) to miss it. Woke it up in the morning to find it had upgraded.
Like you, I'd left the beta program after the final 11.0.1 upgrade. Note lack of text saying I'm on the beta on the left under the icon. (I turned off automatic updates *after* that...)
No actual *problems* with it noticed so far, but...
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