What did Rachel mean when she stated that Hashem had judged her...?
Rashi: She meant that Hashem had initially judged her and found her guilty (which is why He withheld children from her), 1 and had now judged her favorably and given her a son (via her maidservant).
Seforno: She acknowledged Hashem's righteousness in withholding from her children, and thanked Him for giving her a son, 'a staff (support for her old age) and a shovel to bury her.' 2
Targum Yonasan: He had now judged her mercifully, accepted her Tefilos and given her a son.
Why did Rachel and Leah refer to the children of Bilhah and Zilpah as sons, and not Avadim?
Seforno, Targum Yonasan (to 30:4,9): Because they set their slaves Bilhah and Zilpah free when they offered them to Yaakov. 1
QUESTIONS ON RASHI
Rashi writes: "'Hashem judged me' -...He judged me and exonerated me." Why does Rashi need to add this to the simple meaning, 'judgment'?
Gur Aryeh: In this case of Dan's birth, there was no judgment (i.e. punishment), only merit. 1
This follows Maharal's text of Rashi. (Some editions of Rashi read, "He judged me, found me wanting, and [then] exonerated me.") Rashi is based on Midrash Raba (71, 7) "Danani- ... He judged me and found me wanting, i.e. 'and Rachel was barren' (29:31). [But now,] He judged me and exonerated me, i.e. 'He has given me [this] child.'"