Just mucking about, and came across this anomaly.
set now to the (current date)
set themonth to (month of now as number)
copy now to now1
copy now to now2
copy now to now3
set month of now1 to (themonth + 3)
set month of now2 to (themonth + 4)
set month of now3 to (themonth + 6)
now & return & now1 & return & now2 & return & now3
#--> {date "Saturday, 27 October 2012 10:49:08 PM"
#--> date "Sunday, 27 January 2013 10:49:08 PM"
#--> date "Saturday, 28 January 2012 10:49:08 PM"
#--> date "Thursday, 20 October 2033 10:49:08 PM"}