You mean you just did the jailbreak at 3.1.2, you are not going to have shsh blogs for 3.1.2,3.1.3,4.0,4.0.1,4.0.2 but only 4.1 because Cydia can only grab what is apple signing at the time of your jailbreak.
You can try and see if you have any shsh blogs stored in Cydia if the previous owner has jailbroken it before.
If you have the shsh blogs, there are two ways to restore or downgrade:
One is to point your hosts file to Cydia
Two is to Start Tss Server and you must store the shsh blogs locally on your computer.
Only then you do the Shift + Restore.
Download your tiny umbrella from here : The Firmware Umbrella
Click advanced option, select 4.0.1 from Device/Version, request from Cydia not Apple , click save shsh blogs. Wait for reply. Post your reply up here.
OMG, you chose the wrong one. Unfortunately, Jailbreakme.com is not compatible with Custom Firmware, if you had used Blackra1n, Redsn0w or Spirit, then you can use Custom Firmware. Let me do some research to see if I can make it compatible.
You might have to wait for 4.1 jailbreak.