Possible pointer dereference

I'm playing with a static analyzer and it's giving out some real error analyzing postgresql code base like the following one

src/backend/access/transam/commit_ts.c 
   return *ts != 0  // line 321 
but a few line up (line 315) ts is checked for null, so either is not needed to check for null or *ts can lead to a null pointer dereference. Same happens a few line later lines 333 and 339