My iPhone 5 is unlocked somehow?

[astral125]

I got my iphone 5, and used my cut down 4s SIM card to activate it (cross upgrade).

I just checked using the below IMEI checker. My 4S is still locked to ATT, but my 5 is showing as unlocked. Anyone else checking their IMEI?

http://dev.mk/iphone-simlock-status-imei-checker/