Celebrating her 64th birthday yesterday, Martha Stewart received an unhappy birthday present from the federal government: another three weeks of home confinement. She was due to go free on Aug. 10, but now, she’ll have to wear the bracelet until Aug. 31. Neither Stewart nor the federal probation office would say why her house arrest was being extended, but the extra time may be the result of this New York Post story from Sunday, which speculated that she may have violated her probation terms by dashing off for a yoga class. (So at least she’ll be serene about being cooped up an extra three weeks.) Her lawyer issued a statement that she ”has agreed to an extension of the terms of her home confinement until Aug. 31.” Which is sort of like saying that I agreed to pay my taxes this year.