Other people have reported this, so I avoid doing it.  You are probably right about what you saw.

Derek - also please note what happens if I raze the outpost. The tile becomes unusable and it leaves the upgrade graphics in the tile. It actually looks kind of cool but I've lost the use of those 4 tiles. In addition, because of this gobble bug I can't place an outpost near New Hallas that is functional...

Confirming the bug.

Outpost should not be razed, since they provide now bonuses to army there is a reason why you want to keep them close to a city.

There is generally problem with borders, and it is a loooong time problem. They do not calculate well, for instance, you can build the city right next to AI' borders and they will not move an inch, but if they build anything close to your border than you are in big troubles.

The problem here is I did place the outpost next to the settleable tile but not on a diagonal... thus it was immediately incorporated into city limits. In fairness, I should have put the outpost on a diagonal and then not build anything near it to avoid it being gobbled up. However, that doesn't negate the bug exists which is unfortunate.

The buildings that you build on the outpost gets transfered to your city. Most of which don't do anything, except for 2: The hightower and the consulate. You can abuse this bug by building an outpost right next to your city in order to build multiple hightowers (expanding your city ZOC all over the map) and multiple consulates (so that your city grows like no tommorow).