Hmm... curious, but not worrisome, I think. Maybe your yeast went idle due to lack of oxygen, and transferring to secondary added enough to let them get a little bit crazy again.
Looks like pellet hop particles to me.
Are you cold crashing it? If not and if the beer was pretty much done when you racked it to secondary there is no need to keep cooling it unless it is very warm where the fermenter is. What was your gravity when you moved the beer and how long has it been since you brewed it?
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