This just appears to be coincidental timing considering that he will have been in command for 2 years when he is replaced which is the typical length for command time:
An Army general has been replaced after reports quoted him as saying U.S. and South Korean special forces have been parachuting into North Korea on espionage missions.
Brig. Gen. Neil Tolley was quoted as making the comments during a conference in Florida last month. Both he and the military later said that no special operation forces have been sent into North Korea.
The military command in Seoul said Tuesday the departure of Tolley is a routine personnel change.
Tolley started his job as chief of U.S. special forces in South Korea in October 2010, and officials say the posting usually lasts about two years. [Army Times]
This whole episode just goes to show why senior military leaders have to be very careful when speaking around journalists. Some of them are more concerned about getting a splashy headline or too misinformed to know they should verify what was said was accurate.