Something might have happened that caused a rebuild of the Delvic cache. When that happens, it can take as long as a few minutes to boot, but it should only happen the first boot after the cache wipe. If the problem persists, you could try to factory reset your phone in recovery or just use ODIN to re-flash MF3 to your phone. I suggest you make sure to read and learn about whatever option you try and understand, there is always risk associated with trying anything.
SGH-I337 (AT&T) 32GB
P-ROM (1st Gen.), De-Odexed, AMDL
Auto-LOKI OUDHS CWM
Make sure you read and understand the "PINNED" threads in the "General" and "Q & A" sections of the AT&T S4 forum BEFORE you ask for help. Use the forum's "search" function to find posts with additional information. You should not expect others to help you if you haven't tried to help yourself first. Also, read, understand, and follow the "XDA" rules.