I received fan art from a reader once and they messaged me privately to give it to me! If you feel comfortable doing that, then that is also another great option! I'd say that you can post it on Instagram if you want. Just make sure to allocate the appropriate credits i.e. that the art is your work and it was inspired by XYZ.
I can't imagine a creator being weirded out to receive one (as long as it isn't wholly inappropriate). Personally, I think fan art is incredibly touching, especially as you're going out of your way to appreciate the creator 