Even though Warren Buffett seems to think the value of UnitedHealth stock is about right, that doesn’t mean investors should ignore the long list of unresolved issues facing the company.

UnitedHealth Group ( UNH 12.04%) has been a solid dividend growth stock for years. Generally, its yield has been fairly low, due to the stock's rising value. Even as the healthcare insurance giant has grown its dividend, its yield hasn't been particularly high or noteworthy.