I received my GC on Sept 28, 2007, but received a letter from USCIS on Oct 15 saying I need to file I90 because they thought my GC was lost in the mailing due to my earlier inquiries. In the first inquiry for myself on Sept 17, I asked why my I485 was not processed yet. In second inquiry on sept 27, I asked why my wife's I485 was not processed. I saw immediate updates right after my call. Apparently USCIS mistakenly thought my inquiries happened after they sent my GC, but actually my inquires happened right before they started processing my case. Can I ignore this letter by not filing I90 because I already had my GC received?