TRACON Supervisor working position experienced a loss of separation event when forgetting an issued climb and momentarily leaving the position to deliver a strip to an adjacent sector involving a potential emergency aircraft.

Narrative

Air Carrier X on departure westbound requested leveling at 10;000 FT to address an issue; initially was given a climb to 15;000 FT. I didn't have miles of room; but I did have some; so I had him slow down to afford him more time. Air Carrier X eventually made the decision to return to the departure airport; so I turned him right to the east. As he was turning east; now 25 miles northwest of the airport; Air Carrier Y departed; I climbed Air Carrier Y to 15;000 FT (northbound) although I had been restricting all my previous departures to 8;000 FT initially as a neighboring airport was pumping out east gate departures at a rapid clip. Turning my attention back to Air Carrier X; I coordinated with the CIC and the next Controller; this took a few moments; and in between coordination I turned Air Carrier Y west; believing he was stopping at 8;000 FT (as all my previous aircraft had been); well below Air Carrier X. I then hand delivered the strip to the next Controller (about 20 FT away); and came back to my scope to make sure Air Carrier Y was stopping at 8;000 FT; since he and Air Carrier Y would be in close lateral proximity to one another. As you can now well imagine; I was quite surprised to see Air Carrier Y at 9;000 FT and climbing. I gave a couple of separate transmissions for Air Carrier Y to stop climb and level at 9;000 FT; which he did; but not before a couple of 'C' error hits occurred. Looking at my strip on Air Carrier Y confirmed my fears that I had indeed initially climbed him to 15;000 FT off the runway. Recommendation; As the FLM in the area; I am the one who always 'runs' around effecting odd coordination; like this. Perhaps that is why I was the one 'on the move' in this situation; and next time I should remain 'at the scope'; and let others do the running around.