Weird problem noticed today...

This has never happened before but in my Bluesound Node 2i today there is - I can it descrbe is as - bass slap or pop, I think just coming from the left Maggie. I pretty much only play loud. My subs are right behind the Maggie (16" or so) and it's definitely coming from the Maggie. Now the DAC on the Bluesound has a lot more boomy bass than the CD player DAC - Yamaha Aventage BD-A1060. So I am thinks my it's signal-related but perhaps it's the Maggies only they are not being driven hard in those frequencies enough to make that horrible sound. BluOs just did an update that is only major change to system today. I probably hadn't played music on a couple weeks and BluOs asked me to do update then I noticed problem - could be coincidental though could this be an amp or preamp issue?
What model of Magnepans do you have?

You might want to do a reboot/reset on the Node2i, just to make sure it didn't get "stuck" when updated.  I just updated mine and didn't notice any anomalies. 
Agree with mofi's suggestion of doing a hard reboot.  Two updates back I had some audio anamolies as well as Spotify disappearing from the main menu.  If the reboot doesn't work you can do a fectory reset but know that it wipes out all data stored......everything.  It will be a complete start over process.  I had to do factory reset to clear things up but it's been flawless since.  
When you asked "if the ribbon "slapping" is fatal"?  I assumed you had a separate ribbon tweeter, (like a 3.6/3.7/20.7) which would be weird if that was slapping.

The 1.7i is a quasi ribbon panel, not a full separate driver, so no, Maggies will slap if over driven.  You really should try to avoid that, but it's not fatal.
Well that's the weird part. We'll see gotta do that testing. As it wasn't being driven any more than it has for 2yrs and suddenly slapping.