It sounds like you have a sticking auto-choke control assembly. The silver arm (shown here in yellow) should move freely and not bind; we discussed this in another thread, and recall that Honda has just issued a Service Bulletin for this problem, and your mower's serial number is indeed in the affected range of mowers.
Ideally, you should have a Honda dealer inspect and confirm the choke control assembly needs replacement, as it will likely be covered under warranty. Double-check with the dealer before authorizing any repairs.
If you want to DIY, you may want to replace the auto-choke control assembly; it is a good idea to also replace the thermowax cylinder at the same time, even if it is not showing any symptoms. Replacing the thermowax is a bit involved, and best done by a trained Honda tech.
Here's how all the rest of the parts go back together: