RobM_ looks like mold to me. Weblike fibers are indicative of mold....especially since it happened after a few weeks in the jar. Bummer is you can't see the spores and they can get in your jars. If you didn't do so before hand always wash the jars in very hot water before using, even if they are brand new. It's hard too tell how dry your buds should be before you put them in jars so its best to order a hygrometer because it tells you how much humidity there is. I inspect them very carefully twice a day at first and then follow the suggestions in the curing tutorial.
After golngt through 4-5 cures I hardly need to use the hygrometers because your learn how they should" feel" but I still use them. I prefer to not use moisture packs like Boveda until they've been curing for a few weeks.. then once they stabilize at 58-62% I put them in the jars (using 62% bags).
Bud rot may or may not be noticeable when you harvest them, especially if you bud is dark colored and your colas are more than an inch in diameter. It usually starts on the inside and works its way to the outside so if you break open a bud it will be brown and soft inside. Yuck.
To help prevent this I inspect buds carefully before I begin the jar cure and if you've made it that far then its likely not bud rot. Also the larger in diameter your buds are the more susceptible they are to bud rot. After I've dried the bud to where I think its about right I cut the large colas down by remove bracts until the largest buds are broken down to thumb sized individuals_if there is too much moisture inside a large cola then it becomes more apparent when you open them up a bit. also will expose any bud mold. To help prevent mold I continue to open the jars every 3-5 days until the fourth week even when they have stabilized, just to check them. If I have any left after six months I transfer the buds from the 1 quart jars to 1 cup jars, pack them tightly, tighten the lids, and put them in the freezer. Then when I want some I pull the jar, warm it to room temp_ the outside of the jar will stop "sweating"_ and then open and enjoy. I have frozen buds from 18 months ago that are just as good as when they when I froze it. Works well for me. Hope that helps.
Throw that stuff away is my advice.... though I have heard that you can make rosin from it
.Not sure I'd do that until its been confirmed by someone who has actually tested rosin made from moldy bud to see if there are any active spores....so trash it for now and be safe.
Bud is good for you if you treat it and yourself right... but mold is nasty stuff!