Foamy/Frothy Breastmilk

Jocelyn
So, I just pumped this milk.  This was one pumping session, the bottle on the left was from my left breast & the two on the right were my right breast.  My right breast (the two bottles on the right) was so engorged I figured it was a good time to pump.  This is the first time I have seen my milk come out this way. The first bottle filled so rapidly & completely frothy.  Any one else have this happen/is it normal?  
*I know that there is no possible soap residue because I had just washed all pump parts & bottles with dapple, then air dried, sanitized, & let air dry again.*