This one seems to happen/not depending on the exact configuration. It looks like the interstage node might be a little off too (tested by attaching stock parts to it)

This one looks like the node is just a little off and it's only noticeable when the decoupler is streched.

The first one is fixed in today's release (uploading now)....

Will look into the second, as I've noticed it myself. Aye, only seems to happen when the decoupler is at its max height.