DirtyGutter 0.3. jEdit 4.5.0 and 4.5.1. Win7 and Solaris10. Oracle Java 1.6.0-23 and 1.6.0-35.
With DirtyGutter provider set to "Simple" (the default value), *Every* folding that you have made a change inside of (since the buffer was opened) and then closed, is re-opened *every* time you save the buffer. Also, when this happens, the buffer is also automatically scrolled to the last folding that was automatically opened (though the caret is still at the correct position).
The folding mode does not matter (indent, explicit, sidekick).
This is very annoying when editing large files with lots of nested foldings. At least it seems to work fine with provider set to "Diff", so it is not a big problem here at work anymore. (Though it took us quite some time to narrow the problem down).