Bug with printing to PDF of an email message

I sometimes notice something strange when printing an email message to PDF. Sometimes the PDF is not saved. No even when I complete this process. After using CTRL-P the pop up with preview of the email message appears. When pressing OK the explorer window opens and I can select the location and type in the document name. I noticed that sometimes automatically in the panel with all messages the NEXT message is selected (an older message not newer), in the middle of the process I describe above. So before I press OK to save the document. When I press OK the PDF is not saved at all. In this case I have to cancel the current proces (by clicking the cancel button in pop up window with the preview). And then still the NEXT message is highlighted in stead of the message that I wanted to print to PDF. In all cases repeating the process of printing to PDF it works fine. That is very strange. And annoying. Did anyone experience this strange behaviour of Thunderbird? (if it matters: this is both with IMAP and POP3 accounts. Even with a POP3 account without automatically request of new messages. I only trigger the POP3 account with F5. But Thunderbird does not select a newer message but an older message that was already in the panel and not just added by automatic or manually checking of email).