Should I be concerned about my dog's more frequent urine accidents?

She is about 7½ years old, an Australian shepherd mix. She was housebroken when we got her, and has always been good about letting us know when she needs to go out. Over the past few months, she has been having a few accidents, and yesterday I noticed that she had three in one afternoon. I have also noticed her cleaning her genitalia more often than usual as well. My wife thinks it is emotional, due to people in the household moving out or coming back. Could this be a result of emotional insecurity, or is it more likely to be a physical ailment. Also, finances are extremely tight, so a visit to a vet or animal hospital is an option only if the need would be urgent or extreme.