upgrade to 2.7.1 not showing in wordpress

I am using 2.7 of wordpress, and when I login it does not show “upgrad to 2.7.1 at the top, or when I go to tools/upgrade.

I have a few other blogs that it does show on and I have upgraded fine, but I don’t understand why It’s not showing on one blog that I use the most.

hope someone knows the answer.