PC Island obelisk available to buy before island is visited

[tornadojack]

Sorry, I'm not sure but it seems to me that I saw island obelisk in Wizard's Tower before I repaired Willy's boat.
Is it intentional or a bug?
Now I can't recheck that since Island is already visited :(

 

[BlaDe]

It is present in the build menu, but it requires ingredients only obtainable from the island.