[Paddlewise] Do your dry bags deflate air quickly?

Greetings!  We're total newbie kayaker wannabees, husband & wife, Ashton &
Leska in Cascadia (Oregon/Washington area), bought 2 recreational kayaks at
REI on clearance:  2002 Dagger Zydecos.  LOVE to paddle them on flatwater!
Did a huge amount of research first, bought the Zydecos because they have a
domed foredeck so moving legs and feet around to change positions is easy.
We're in our 40s and after decades of caregiving have sore backs and creaky
bods.  Also on the accumulated advice at paddling.net splurged on 2 Werner
bent shaft Kalliste paddles to help save wrist / arm / shoulder injuries and
pain.  

Been lurking for a while at paddlewise eMail trying to glean facts from all
you experienced experts:  great list!

To the dry bag question plaguing us at the moment:

Got Seattle Sports brand, Hydro Venture Glacier Clear Dry Bags, small &
medium sizes. Filled them about 1/3 with emergency fleece clothing in case
of dunking, rest of space air. About 1/2 hour after sealing, air has
deflated _at_ 50%. Bags limp squishy soft -- won't stuff as tightly into bow &
stern spaces for max floatation.

Is this quick air deflation normal? ???

Bought them for dual purpose: floatation and keeping gear dry.

Wondering if the brand is bad (sold at REI & Andy + Bax in Portland, Oregon)
or if all dry bags do this? Have filled many times to test; always deflate
within 1 hour. 

If air seeps out so easily, does that mean water will seep (or flood!?) IN
just as easily? 

Have not actually used these outside yet; they haven't gotten wet; just
practicing loading 2 new recreational kayaks (Dagger Zydecos); can return
these dry bags if they're malfunctioning.

What's normal? 

Thanks for your help!  
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