I don't play survival too much, but I'll try to get on and see what's wrong with it.

 

The blocked off a larger area to prevent more spawn issues.

 

Oh yeah I remember that lol it just says "sorry but you can't break that block" or something

 

Then you obviously weren't in the blocked of area.

 

I believe it's a protected area, if it wasn't protected yesterday by you then someone else may have protected it during the time you were offline.