I'm a Dr. Gross patient, 4/11/12. I posted about the dressing too, though not out of concern, just curiosity. I didn't have any dressing stuck, just lots of black glue gunk. I took the two bandages off at nine days post surgery. The vast majority of the black glue (or whatever) that was holding the main bandage on (around the periphery) stayed on for twelve more days (so twenty one days total post surgery) no matter how much I scrubbed it in the shower. I really tried to get that gunk off, no matter how much I irritated the area. It really didn't work. It came off when it wanted to come off.
Getting rid of it (for me) was a significant post surgery milestone, but nothing I did appreciably accelerated the process.
Just over seven weeks out and I am stunned at how minimal my scar is and how little raised it is.
Just re-read your post. Unless you are having an issue with the incision itself, I think you are supposed to leave it open to the air (after you take off the sealed bandage, which you have). I am not your doctor, though, so please don't rely on my opinion.
Good luck!
Mike
P.S. The black gunk was more than simply around the perimeter. It was everywhere under the bandage EXCEPT FOR the very narrow ribbon (less than a centimeter) of the actual incision itself. So it makes for a very unappealing black gunk tattoo for 12 days or so. They must squirt the black glue on the butt cheek ITSELF and then slap the bandage on it to get such precision. Just a guess, though.
Put another way, the area looked a lot like one of those lightning bolt military patches; a dark rectangle (of black gunk) with a light line (the un-gunked incision) down the middle.