What did it smell of?

If urine, the strange behaviour could be a sign of difficulty
urinating, in which case get him checked out for crystals or impending
blockage.  Or at least closely watch his urination habits and see if
there is anything new or different.  If he repeatedly vibrates his
backside when peeing, or trying to pee, that's an indication to check
him out.

Very unusual for a housetrained cat to do that directly on you, but
maybe he really was trying to give you a message....directly!

Good luck.

--tension