Parashat Naso, in Numbers 5:1-3, presents a commandment to "send from the camp" anyone who is tamei due to either tzara'at or a zav-type discharage. After that, we have Verse 4, affirming that the Israelites did as commanded:
וַיַּעֲשׂוּ כֵן בְּנֵי יִשְׂרָאֵל וַיְשַׁלְּחוּ אוֹתָם אֶל מִחוּץ לַמַּחֲנֶה כַּאֲשֶׁר דִּבֶּר יְהוָֹה אֶל משֶׁה כֵּן עָשׂוּ בְּנֵי יִשְׂרָאֵל
The children of Israel did so: they sent them outside the camp; as the Lord had spoken to Moses, so did the children of Israel do.
It seems to me that this commandment was meant to apply in perpetuity and was not a one-time expulsion. If so, it seems atypical that the Torah would record the fact that it was adhered to the first time. (One other example that comes to mind was a record in Numbers 9:5 that the Israelites performed the first Korban Pesach after the Exodus, but I can see various reasons for that, including that it was leading into the Pesach Sheini story.)
Am I right that this sort of "and so they did" is atypical for commandments meant to apply in perpetuity?
If so, why did this commandment, in particular, get such a record?