The Colombian attacker, who is on loan with Millonarios, is being heavily linked with a shift to the Portuguese giants and is feeling calm about the proposition according to Henderson.
"I don't know where it's at, at this point, but I know he's optimistic and feeling ready. But I don't know exactly where it's at," said Henderson.
"For Fredy the experience of trying something else I think he had great success here with the Sounders, so for him to be able to try it in Europe or try it in South America again to see where he's at I think was great for him.
"As I said, he was very important for us in our success in getting to the playoffs every year and winning Open Cups, so I think we're both happy where we're at. I think he has great feelings toward the club. You never know in the future to see Fredy back in a Sounders jersey would be great for everyone."