P31 Controller witnessed a developing conflict involving traffic in an adjacent sectors and called the affected sectors alerting them to the developing situation.

Narrative

This was a situation that occurred on the border of P31/MOB airspace; at the TRADR fix/gate. After I handed off and shipped Aircraft Y to MOB Approach; on course; level at 100MSL Westbound to TRADR. Shortly thereafter; I accepted a hand off on Aircraft X; about 12nm West of TRADR; level at 110MSL Eastbound to TRADR. I observed Aircraft X descending into the opposite direction Aircraft Y; still level at 100 MSL Westbound. I call ZHU Brookley Sector; who owns the airspace at 110MSL; over MOB Approach. They stated MOB was talking to Aircraft X. I then called MOB West Sector to announce the immediate traffic situation. They stated they were taking actions to avoid the traffic. At no time were either aircraft were on my frequency for this traffic event. I had transferred communications of the Aircraft Y before I took the hand off to Aircraft X; which would have been 5-8 minutes before this event. I simply saw an unsafe event and took actions to bring this unsafe action to the attention of the controller involved. Trying to BREAK the CHAIN; so to speak. I do not know what would help this event. It is normal to receive IFR arrivals 1000 ft above outbound IFR traffic. In this case I do not know what coordination occurred between ZHU/MOB as to why MOB would be talking to Aircraft X at 110MSL; above their airspace; to an aircraft inbound to PNS; and to why they descended Aircraft X with traffic opposite direction 1000 feet below them.