Air Suspension Woes

[DRZDuke]

I just had a new ride height sensor and Air system Module installed my H2.
All seems to be working as it should, however, when I shut the truck off for any more than 1/2 hour, the rear air seems to bleed down.
As soon as I fire the truck up, compressor kicks in and pumps up the Hummer as per usual but it didn't operate this way before I had the issue with the suspension.
Is this a programming issue ? The tech that replaced the electrical components assured me there were no leaks in the bags(which I replaced last year)
Any help would be great.