I don't think my Ale Pale has a gasket in it- it's covering my primary right now. It does fit TIGHT, though. I almost have to use a pry bar to get it off, and I have no leaks.
That is interesting that some of the fermenter buckets that are sold out there come with lids without o-rings. I did not know that. All the ones that I have seen have had o-rings, even the cheap 5 gallons buckets from Home Depot that I use for misc cleaning and sanitizing tasks. I guess you can learn something every day if you look hard enough.