Thumper spear clog?

[BlueJ]

I have a 15.5g keg and a 7.5g keg thumper running on electric. Today it was charged with about 8g of clear mash and the thumper with about 2g of murky corn meal from the bottom of the fermenter. I set this up in a cold garage last night and it sat overnight to run today. During heat up, I got normal action in the boiler and a few pings from the thumper, then the thumper stopped making noise. It does quite down once up to temp so I didn’t think too much of it, but all the sudden Ingot a huge loud “whoosh” from the boiler column I to the thumper and it immediately started to bubble and quickly boil in the thumper. I added a sight glass to this run so I could see the vapor rushing up the column like it was shot out of a jet engine for about 3-4 seconds. My butt puckered up something fierce. Running absolutely fine and normal now.

I think maybe the sitting overnight and the first few hot bubbles of vapor from the boiler dried up the corn mash in the thumper and sort of made a biscuit at the end of my spear? Is that possible? Then the pressure built and pushed through the clog. My spear has holes and cuts around the bottom to disperse vapor. Not sure what I did wrong here.

Anyone experience this and have suggestions. I read one thread that said the little holes could get clogged but I would think the 1” pipe open at the bottom of the spear would not.