Net::SMTPS=GLOB(...etc...)>>>> EHLO localhost.localdomain
  Net::SMTPS=GLOB(...etc...)>>>> 250-smtp.gmail.com at your service ..
+.
  Net::SMTPS=GLOB(...etc...)>>>> 250-SIZE 35882577
  Net::SMTPS=GLOB(...etc...)>>>> 250-8BITMIME
  Net::SMTPS=GLOB(...etc...)>>>> 250-STARTTLS
  Net::SMTPS=GLOB(...etc...)>>>> 250-ENHANCEDSTATUSCODES
  Net::SMTPS=GLOB(...etc...)>>>> 250-PIPELINING
  Net::SMTPS=GLOB(...etc...)>>>> 250-CHUNKING
  Net::SMTPS=GLOB(...etc...)>>>> 250 SMTPUTF8
  Net::SMTPS=GLOB(...etc...)>>>> AUTH LOGIN
  Net::SMTPS=GLOB(...etc...)>>>> 530 5.7.0 Must issue a STARTTLS comma
+nd first ... Authentication (SMTP) failed
[download]

but note that one of the messages confirmed STARTTLS already.

Are you sure? I only see an SMTP server identifying as smtp.gmail.com announcing its capabilities conforming to RFC1869, which are 8 bit MIME messages, TLS encrypted communication, enhanced status codes, and so on. I don't see any TLS confirmation here. RFC2487 documents that the EHLO command needs to be followed by a STARTTLS command. Your output shows AUTH LOGIN instead.

Alexander