A: Lemons and limes are “ever producers”, which means if the conditions are right, they continue to bloom and produce fruit. You obviously have this plant in a well protected area which must receive sufficient light and water. Therefore, this lime tree is happy to keep making fruit. If it has gone through temperatures in the teens and still produced fruit you have little worries. You can always cover it if temperatures drop below freezing. However, you are doing something right already so I would suggest doing nothing to alter perfection. Your patio may be a micro-climate where the temperatures are conducive to citrus production. This lime may also be on a dwarf tri-foliate root stock which is very cold hardy. All of these factors have contributed to your success. Keep up the good work; we are all envious.