I deleted each file and found out that the readme.txt is causing the false positive. Remove the readme.txt and able to install without problems. I shall let my hosting provider know about this. Wonder what phrase triggered the false alert though.
I have installed previous versions without issue, am currently on Version 3.2.1. My installation procedure is to upload the plugin (which I download from wordpress.org) using file-manager in cpanel into the plugins folder and unzip the upgrade. This time, however, the zip file does not show up, despite repeating the procedure carefully. I then used cpanel legacy file manager and the virus detected prompt showed up. Before I rattle at my host provider for false alarms, I hope someone here can clue me.