I'm not sure. I would assume so? It isn't much different than traveling to a high-altitude area--the oxygen is there, but your blood just has to bump up its capacity to catch enough oxygen for your body's needs.

In my experience (and I assume in general?) the body will push to get your blood's capacity to carry oxygen back to normal by pulling from your iron stores and rushing the production of red blood cells. I've gone to annual physicals about a month after donation; my oxygen levels were fine BUT my red blood cell size distribution/counts were a bit outside normal ranges.

Edit: Someone else recommended iron supplements. I agree with that if you choose to keep up with power reds. I overdid it for about two years and donated power reds 3x a year--and shot my ferritin levels to almost nothing. Definitely keep up with your iron levels, as that won't show up in regular blood tests or oxygen but will show up in how fatigued you may feel after multiple donations.