I agree with your general thoughts, but he definitely wasn't back in "3 weeks" either.
Here's what really happened:
"Danny Amendola has confirmed that he will be back in action for the St. Louis Rams in Week 10 following the team's Bye Week this weekend.
"Yeah, absolutely," Amendola said, according to an Associated Press report (via ESPN.com). "I'm ready to come back and I'm ready to do what I can."
Before being injured in the second quarter of the team's Week 5 game against Arizona, the Rams WR was among league leaders with 34 receptions and 395 yards receiving.
That's at least 5 weeks right there.