Google Play *store* and Google Play *services* are two different things. Some models are behind on the Play *services* update because Google has not issued it for those devices yet, or they did not want to issue an update for the sake of issuing one if they had nothing to fix. No one seems to know the reason. So, it's nothing you are doing wrong, it's totally a Google issue.
It's interesting how you are stating that "Google Play Services" has not been updated HOWEVER "Google Play Services" has indeed been updated yet the "Google Play Store" has NOT updated since September/October on some phones. I totally agree that it is a Google issue. It is important to differentiate which application is not updating correctly as they are 2 different applications. "Google Play Services" is used to update applications on Google Play Store as well as Googles own applications and is indeed updating. Google Play Store is not updating. I'm just explaining for those who do not understand the difference between the two and are reading the posts.
Oh, please. Maybe they did not update because they did not find any security holes that needed to be plugged. Ask them. Not a Samsung issue. It's a Google issue.
The yellow triangle usually indicates an issue with an update. Try clearing cache and/or data for the Play Store. Try restarting your phone for good measure.
