As long as the sub donor was known to be drug-free (that includes scripted/OTC meds), and had not consumed a large volume of fluids prior to giving you the sample, you have nothing to worry about.

And as long as you didnt spike your sample with adulterants containing nitrites, chromium, or glutaraldehyde, then you have nothing to worry about. The use of other forms of adulterants will cause an abnormal pH.

Frozen urine stays "good" for up to 12 months.