Is this your first batch of homebrewed beer? Often times when the FG has been reached, there are still compounds like acetaldehyde that can taste rather tart. This is a normal part of fermentation and the yeast will clean it up while in the bottle. It can be amazingly bitter if you are not used to it.
Bottle it and enjoy.
EDIT: Gravity is ready for bottling when 2 samples taken 3 days apart are the same. It sounds like you have a lot of honey to get rid of, priming with honey could be fun.