Sourdough SCOBY?

I’ve been making sourdough on and off for years.  This batch was parked beside the kombucha tea urn.  Is that why it formed a kombucha tea-like SCOBY,  or biofilm? This is the first time I’ve seen this happen.  Beneath the layer all was well,  the sourdough smelling nice and spicy.  I took the layer off and fed the sponge.  It’s bubbling away as good sourdough starter should.