Kent & Alan,
Cleaning your brush between sessions is NOT suspending it in MS. What I see looks like very small partially cured finish specs from the brush. Clean the bush very well; then suspend it in MS. No need to go to the soap and water steps.
Otherwise you get little specs of finish that can't be seen in the wet finish; then, YOU SEE them when it dries.
Scott
Finishing is an 'Art & a Science'. Actually, it is a process. You must understand the properties and tendencies of the finish you are using. You must know the proper steps and techniques, then you must execute them properly.