I have been made aware of a rare bug that may only impact Safari users. The exact cause is unknown but most likely cache-related. It can cause JSON to be served up instead of HTML for new posts.
I believe that 99% of users will most likely never see the bug but I have attacked it anyway.
I took a long hard look at the cache rules and tweaked them in the hope that this fixes things. It seems to have. I think it is solved once and for all but time will tell.