I have a kaffir lime tree in a pot that's been doing really well for a few years. Just noticed last night when watering that some of the leaves around the base have black spots. Is this anything to worry about? The tree seems overwise healthy and I've been trying to remember to water and feed it regularly. It doesn't seem to be any of the problems listed here - http://www.yates.com.au/fruit/tips/solving-citrus-problems
