告诉你爸要当心了，长期出国太频繁。

“这么多年一直没事”不等于永远没事。你爸这么多年每年都回国超过半年，有什么具体原因？还是觉得中国舒服？舒服就别要绿卡么。

那么多次，总会有一次边境官看不下去了，给他个警告。 你不能以为“这么多年一直没事”来想。

为什么不申请回美证？

http://www.cilawgroup.com/news/2015/05/06/green-card-holder-and-i-327-advised-passport-notation-what-to-do/

I Received “I-327 Advised” Notation – What Should I Do?

We recommend that you consider obtaining a reentry permit as soon as possible.  Depending on the travel plans and how long the applicant will plan on staying in the U.S., there may be a number of filing strategies.  We certainly recommend that a reentry permit is, at a minimum, filed before departing the U.S. so that during the next entry into the U.S. there will be a proof that steps have been taken to comply with the “I-327 Advised” notation.