I have an older (15 yrs), smallish gas furnace/AC unit, that's sole purpose is to supply heat for a room addition. I'm not at home so I don't have the particulars handy, but it sits in a closet and is about 4 ft tall. I had to replace the limit switch a couple years ago, otherwise it's been great. This year, I've noticed that after a heating cycle (that is the burners light, temp comes up, blower kicks on, eventually burners extinguish, blower runs another minute or so, then shut off), the blower will come back on after maybe 1 minute and run for maybe 10 seconds then shut off again. Then all is well until the next cycle. Should I be worried about this odd behavior?