If you withdrew from your TSP in the year in which you were 55 or later, you should not be accessed an early withdrawal penalty.
See excerpt from link below:
'If you receive a TSP withdrawal payment before you reach age 59½, in
addition to the regular income tax, you may have to pay an early
withdrawal penalty tax equal to 10% of any taxable portion of the
payment that is not transferred or rolled over.
However, if you separate
from service during or after the year you reach age 55 (or the year you
reach age 50 if you are a public safety employee as defined by section
72(t)(10)(B)(ii) of the Internal Revenue Code), then the 10% early
withdrawal penalty tax does not apply.
https://www.tsp.gov/LifeEvents/career/enteringRetirement.html
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