Uncollected Social Security Tax

I have had the maximum social security tax withheld from my employer. A previous employer with whom I still hold a group universal life policy send me a W2 with an amount of $44 listed in Box 12 Letter Code M (uncollected SS tax). TurboTax is adding this $44 to my tax liability even though I am, as I already stated, at the maximum. Why is it doing this? Is it a bug or am I not understanding the tax law?