If a large number of NK soldiers go to Syria and come back victorious, that would certainly a concern. For now, it may not look as if it would reach such a level.
It's one thing for North Korea to send small groups of special forces to be mercenary “palace guards” for Assad. (Actually, it's probably a really good idea for Assad who can't necessarily trust his own people.) But a large-scale deployment of North Koreans, or a deployment of enough North Koreans to come back and influence the North Korean leadership to send them out again to win more battles, could be a truly horrible development.
As you know, Tiger, Korean troops on both sides of the DMZ are known for iron discipline. There are reasons why the US Army accepted President Park's offer to use South Korean troops in some of the nastiest engagements of the Vietnam War. Sending highly disciplined and aggressive North Korean troops into the Arab world, where military forces are not known for discipline, could create all sorts of problems. The Communist Viet Minh and Viet Cong ran from South Korean troops during the Vietnam War, due at least in part to some of the most horrible reprisals imaginable by South Koreans troops against Vietnamese Communists.
If Arab insurgents decide that North Koreans are as dangerous as the Vietnamese Communists thought the South Koreans were, North Korea will get a reputation all over the Middle East for fierceness. Getting a reputation for fierceness and toughness in battle is not irrelevant in the Middle East.