Go into your fridge, grab a commercial bottle of beer, one that was capped at a plant. Give it a good shake...and you'll see foam.
It foamed because when you were putting it in the fridge or when someone was rooting it the fridge, the beer got agitated.
Usually the most LOGICAL answers are the right one...You're wife moved it like you said.
It's not going to dissipate all that fast, because the beer's in a sealed environment, the only way for them to break down is for their surface tension to degrade, there's not going to be anything necessarily breaking them.