Ok...
I did some Googlin' and my memory was jogged. I ran into this same problem when I got my first smartphone (a Droid Inc) a couple years ago. I don't think this is a platform-specific issue as I saw it on that Incredible. Google defaults to sync'ing events that are less than a month old. The work-around that I have successfully used on the Inc and now my S3 is to export and re-import your calendar(s) that you want sync'ed past the previous several weeks.
To do this, you'll need to go to open your Google Calendar with a browser and go to the settings page. Once there, hit the "Calenders" tab. From there, click the link "Export calendars" and save the zip file to your computer. Unzip the file. For each calendar you want to reimport, click the "Import calendar" link, select the appropriate unzipped .ics file and the appropriate target. It sounds a little scary but this process did not screw up any of my events or create any duplicates. The theory is that it updates the modified timestamp of all events so they'll be sync'ed to your phone.
Here's the post I found that helped jog my memory:
Yahoo! Groups
As with all web-advice, YMMV and proceed with appropriate caution. This was the second time I've had this problem with 2 different phones and both times, the export/import method worked for me without screwing up my data.