Gas pressure after bottleing?

Today I bottled up some apple wine after stabilizing with some wine conditioner/sweetner as well as adding a little apple juice to increase the flavor a little bit. I had a little left over which I put into a sealed mason jar (for drinking later)!. A little later (3 hours) I noticed that the lid to the mason jar was under pressure so I unscrewed it to relieve the pressure. Next I unscrewed the screw caps on my wine bottles and a little gas came out of them as well. My SG was .997 when I bottled it so I am sure that I have no fermentation going on. Is this a normal thing which happens after wine is racked and then bottled?

.997 is not really done. You should have let it sit a while after back-flavoring.

doctor cad how do you know that .997 is not done???? if you take an SG reading about once every 7 days and it stays at .997 then it is done.....not all wine goes below .997

I think you're best off waiting a bit before adding more sugar (apple juice) to let the stabilizer do its thing. Maybe some of the surviving yeast got at the juice before it died off?

It could be a result of a wine that still had dissolved CO2. Are you confident it was degassed thoroughly?

I'd tend to lean toward CO2 in the wine. When you added pot met to stabilize, it likely started to replace the free SO and thus released gas. Could have been too slight to see as you're racking into bottles, which also disturbs the wine causing more gas to release. That coupled with the short time of just 3hrs from bottling to noticable pressure in the jar...