Battery light blinks before startup but not after

Symptom: I stick the key into the
ignition, turn to the first click all the
dashboard lights turn on as usual,
with one small anomaly: the battery
light now blinks (before starting up
the vehicle).  Then I start up the
vehicle, and the light, along with all
the others, goes off, as it should.  
Everything seems fine, engine sounds
smooth, vehicle runs great.  Should I
be worried?

BACKGROUND: 2008 Toyota
Highlander, V6, 4D, 2WD,
101,587miles, mechanic just replaced
alternator, 14.17v coming from
Alternator to battery, Walmart and
O’Reilly both tested the battery and
performed drop voltage test on
battery and said all is good!  The
battery light never used to blink
before starting up. Now, after
receiving it back from the mechanic,
it does.  But no problem after startup.