They do this in wine too...you do have some trapped are within the pores of the wood that works its way out but nothing of concern. This is why Budweiser Beechwood ages....lots of surface area and nucleation sites.
Something is always fermenting....
"It's Bahl Hornin'"
Kegged: Sour Saison, Pale Ale, Aggie Ale, Firestone DBA, De Koninck Blonde
Bottled: Belgian Quad (Grand Reserve), Derangement (Belgian Dark Strong)
On Deck: Pliny the Younger