Barb, these words are used in accordance with a  specific bit of the Law, like virtually all things Yashua did. As the words on the cross fulfilled Prophecy, these after resurrection proceed even to show the Law.

For it is written,

Num 19:16-19
16 And whosoever toucheth one that is slain with a sword in the open fields, or a dead body, or a bone of a man, or a grave, shall be unclean seven days.
17 And for an unclean person they shall take of the ashes of the burnt heifer of purification for sin, and running water shall be put thereto in a vessel:
18 And a clean person shall take hyssop, and dip it in the water, and sprinkle it upon the tent, and upon all the vessels, and upon the persons that were there, and upon him that touched a bone, or one slain, or one dead, or a grave:
19 And the clean person shall sprinkle upon the unclean on the third day, and on the seventh day: and on the seventh day he shall purify himself, and wash his clothes, and bathe himself in water, and shall be clean at even.
(KJV)

Thus Jesus fulfilled this part also, for for 3 days and nights did visit the prisoners, and on the third day the clean person did sprinkle, and Jesus dead body did arise.

Thus He did tell her, 'touch me not' even in accord with another passage,

Num 19:22
22 And whatsoever the unclean person toucheth shall be unclean; and the soul that toucheth it shall be unclean until even. (KJV)

After the purification, on the EIGHTH day, He showed Himself and was touched by the doubting, being cleansed, as we are for ever more from the curse of death.

26 And after eight days again his disciples were within, and Thomas with them: then came Jesus, the doors being shut, and stood in the midst, and said, Peace be unto you.
27 Then saith he to Thomas, Reach hither thy finger, and behold my hands; and reach hither thy hand, and thrust it into my side: and be not faithless, but believing. (KJV)

Thus having fulfilled all the Law in His flesh, we march on to the fulfillment of the prophets..........