I opened my email client, rarely used, to find an email from my credit card company asking for verification of a purchase. The email looked very genuine and gave the correct contact details. I was suspicious as I have not made a purhase. My webmail does not show this email neither does Thunderbird nor gmail. Also strangely this email is not showing on my tablet. The credit card company say there has been no suspicious activity. Is it likely that my pc is infected in some way?