Then you've done well - do not, for one minute, worry about changing the domain name just to spam an extra keyword or two in there. Would you tell Amazon to rebuild as amazon-merchandise-bargains.com? Or to buy that domain and redirect it?
And the redirection scheme is a bit toward the spammy side. Actively promoting domains that gain ranking but then redirect is not an approach Google appreciates. I say full steam ahead, building further on what you've already achieved.
The one way that this make sense is if you have a keyword domain that gets natural type-in traffic. But not if you need to actively promote a domain name that then redirects.
Not necessarily, not at all.