Henson had been eager to get back on the field and prove his fitness ahead of Wales' RBS 6 Nations Championship match in Ireland.
He said: "It was good to get back on the field but I had forgotten how hard it was.
"I was rusty. My place kicking was good but my kicking out of hand was inconsistent.
"I'd love to play for Wales next week but it's out of my hands."
Henson was watched at the Liberty Stadium by Wales caretaker coach Scott Johnson who has taken over for the remaining three championship games after the shock resignation of Mike Ruddock.
On the resignation of Ruddock, Henson said: "He was good to me. He always picked me. It's a pity he has gone.
"Scott Johnson had good ideas but we will just have to wait and see what happens."