fopen() fails with ENOENT but open() works. WTF?

gistfile1.txt

Verbatim LLDB session with an iPad Air running iOS 7.1.1.
As you can see, "finPath", which is a const char*, is an absolute path.

Normally fopen(finPath, "r") works fine but sometimes after stress-testing the app gets into a state where it always fails with ENOENT.

How could fopen(finPath, "r") fail with ENOENT while open(finPath, O_RDONLY) succeeds?

Edit: forgot to say that no memory warnings were received during the stress test.

(lldb) p finPath
(const char *) $17 = 0x00000001702dcfd1 "/var/mobile/Applications/91616646-D71F-451D-A14D-EC2BA61B99A5/Documents/inttest5/pdf/00002014"
(lldb) p (FILE*)fopen(finPath, "r")
(FILE *) $18 = 0x0000000000000000
(lldb) p errno
(void *) $19 = 0x0000000000000002
(lldb) p (int)open(finPath, 0)
(int) $20 = 275
(lldb) p (int)close($20)
(int) $21 = 0

Turns out that the app was leaking FILE*s. Case closed.