Wait one sec, "loan?"
Most retirement plans don't allow loans. If you mean loan informally, as in "I withdrew money planning to pay myself back" that's fine, it's just a confusing use of the word "loan."
If this was a formal loan from a retirement plan that allows loans (401k, 403b, possibly others) the rules might be different. You should not have paid any tax on a real loan as long as you had not defaulted on the payments. If you had a formal loan, we may need more information.
