Scan email content: "Common ports missing from Services"

I'm not sure if this is expected behavior but it seems a bit odd to me. If I create a firewall rule with the 'Services' to to 'Any' and subsequently select some options under 'Scan email content' such as 'Scan POP3' (this applies to any of the options), there's a small text dialog that says "Common ports missing from Services for POP3". If I click 'Add Ports', it will add 'POP3' to 'Services' thus removing 'Any'.

It would seem if I already have services set to 'Any', I shouldn't be getting the small text dialog prompting me to add POP3 ports.