FFF
Can and does happen - I have a friend who works for a lj manufacturer, who confirms that they have had some "airline" type jackets back from customers for servicing (annual, bi-annual, something like), and on pressure testing, have found some have patches where the air leaks out (albeit very slowly).... they talked to the customers involved, and deduced that they were worn constantly in the air. The porous patches of the jackets lined up nicely with the line of the seatbelts, which over time have quite an abrasive effect.
This is probably very dependent on the aircraft type and jacket type used, but the problem should be alleviated by using more heavy duty jackets. Incidentally, the heavy duty jackets are rumoured to often better at getting your head up out of the water more quickly, and keeping it there in choppy seas.