I own a small rental house, and adjacent empty lot.  Another investor who owns owns the lot behind mine, contacted me to sell the empty lot to him, or buy his, since he doesn't have street access from his lot.

Empty lots starts pretty close to the wall of the house. Normally I would prefer to sell both together (thats how I got it) since house would not have much room around without the empty lot. 

But since all I have been doing is paying property taxes on the empty lot, not averse to selling either. 

Anything I should be careful about in this scenario? If I sell only the empty lot and keep the house, could anything pose problem for me later on? On surface seems like a simple scenario, but this is the first time I had to think about something like this so trying to make sure I have a better idea before I make decisions. 

That area is slowly getting gentrified, prices in the area expected to increase, as usual speculation.