As it crosses the 7th house cusp (DC) there could be problems in your personal relations to others. In a love relationship, or other people in general, there could be increased aggression or arguments.
Into 6th, increased chance of health problem or accident, but unless it aspects a planet in your 6th or aspects the ruler of your 6th, there will likely be nothing. As the 6th also rules the workplace and co-workers, could be some problems there.
Mars retrogrades happen every 2 years, we usually don't even have any problems at all from them. Look at your transits from the previous ones, and other people's transits, usually just minor annoyances, easy enough to handle.
I mainly wrote the OP to let everyone be aware of what could potentially happen, and for information in general.