I noticed the other day that my hands were getting too much of a workout because my grip on the boom kept slipping. Perhaps I've got a bit of grease or wd-40 on the boom, or perhaps the rubber is just too damn smooth. I suspect the former, because the same thing once happened to the deck pads on an old board and made the rubber super slippery.

Is there anything I can do about this? Some miracle fix? Re-gripping the boom sounds a bit drastic, as the rubber is still fully intact. It's an old old old NP carbon X9, btw.

could be sunscreen residue.

give the boom a wash with warm soapy water.

as gestalt said, was your boom with soapy water...
also, put the sunscreen on while your still at home then wash your hands too.
if you need to re-grip, you can't go past elastoplast faric tape wrapped around lots and lots, a bit rough to start with but goes good after about 2 sessions and sticks forever.

Just gently scratch you grip with some cissors or a knife (you can do with your nail as well ) to take a small amount of surface off and then rince it.
Or if you're not confident with that, use sandpaper.