[gentoo-user] Autoexecute when "returning" from sudo ?

Hi,

often I have this scenario:
I miss an application/script, a setting or something like that.
To apply the modifikation I becom root from the shell I was using as user. 
I modificate/install or whatever change is needed...
I CTRL-D back to my user shell.

Now I have to do a "rehash" (I am using zsh) to make the change
visible/accessible. Sometimes I forget that.

So...is it possible to auto-execute a "rehash" or whatever is needed,
when the user is comeing back from his alternate life as root?

Thanks a lot for any help in advance!
Cheers!
Meino