It is more looking at a pattern than a concrete set of rules. Your first post said "you were reminded at the port of entry that if i stay more than 6 months i could lose my GC". This likely implies they also noted this against your file in the computers and the next time you come into the country, they will check this aspect again.
I am sure you can go for another 3-4 months trip easily this year ... after a couple of months break in US. Go after a week or 2, and you risk breaking continuous residence.
GC: EB1: 1999 ==> 2004. 3 yr delay due to lost file. N400: San Jose. Apr'09 ==> Aug'09.
I am not a lawyer, forum police, moderator, moralizer or an immigration officer. If I sound like one, use "your" best judgement.