Jim,
I'd ask before you do it, just to be sure.
Some of the game laws can be a bit odd in their applications.
Personally, I never use any subsurface fly that hasn't been treated with a masking liquid. I fish mostly for bass, and have proven to myself that offensive odors left on a fly can and will negatively effect my catch rate. Do it for trout flies, too, but no clue if it helps. No reason I can see to do it with floating flies.
We seldom have any control on what was put on or used on the materials we purchase, and the use of glues, cements, and such has the potential to leave negative odors behind. Add to that what may be on our hands from everyday activities, and I just think it's smart not to take chances with it.
I do it at the bench, as part of the tying process. It's the 'last step' before the fly goes into it's bin.
So far, I've never been approached on any C&R water I fish and 'asked' if I scent my flies. But then again, I've never even SEEN a game warden on any of these waters...they tend to hang out in the parking areas looking for poachers...
Good Luck!
Buddy
It Just Doesn't Matter....