AN ACR DC9-32 FLC; DISTR BY WX; CLBED ABOVE THEIR ASSIGNED ALT. NO CONFLICT.

Narrative

WE WERE CLBING OUT FROM THE SURFACE TO OUR ASSIGNED ALT OF 2000 FT MSL. I BECAME DISTR BY SEVERE WX AND WAS WATCHING THE RADAR. I DIDN'T HEAR THE '1000 FT PRIOR' ALERT AND NOTICED MY ALT WAS UP TO 2300 FT MSL (300 FT HIGH). I PUSHED THE ACFT OVER AND CORRECTED THE ALT. WE WERE BUSY; BUT I SHOULD HAVE BEEN 'FLYING THE PLANE' WHILE THE CAPT WORKED THE RADAR AS I DISCUSSED ON MY 'TKOF BRIEFING.' FAA WAS ON BOARD IN COCKPIT JUMP SEAT. THE CAPT QUICKLY ASKED IF WE WERE CLRED TO A HIGHER ALT. ATC REPLIED; 'YES; I THOUGHT WE CLRED YOU TO CLB AND MAINTAIN 10000 FT.' THE CAPT ALSO ASKED IF THERE WAS 'ANY OTHER TFC IN THE AREA.' GULFPORT TWR REPLIED; 'YOU ARE THE ONLY TFC WITHIN 40 MI.' NEITHER ATC NOR FAA MENTIONED THE ALT EXCURSION NOR DID WE ASK IF THEY NOTICED IT VISUALLY; MEANING THE FAA ON THE JUMP SEAT OR BY ATC USING RADAR. TO THE BEST OF MY KNOWLEDGE; THE FAA (WAS A MAINT INSPECTOR) WAS NOT AWARE OF THE SIT. IF ATC DID NOTICE; THEY DIDN'T ASK US TO CHK OUR ALT. IF THEY (ATC) DID PREVIOUSLY CLR US TO 10000 FT; WE ALL MISSED THE RADIO CALL AND THERE IS NOTHING TO RPT; OTHER THAN A MISSED RADIO CALL.