Problem with search contacts for sending SMS iPhone 3G

Since the last firmware upgrade, I noticed that whenever I look up a contact and select his/her mobile number and then select the text message, the message box appears addressed to the previous SMS target. So, If I had just texted my boss and then decide to send a love message to my wife, my boss will get the wrong impressions if I am not careful! Although funny, this is a very serious bug because of the repercussions it may have. To send the message to the right person, you would have to cancel and relocate the correct person on contactsto repeat the process.
Windows Vista