Don't freak out about them being in your Sent folder. Remember that Gmail doesn't have "traditional" mail folders -- just a huge pile of all your e-mail messages with "labels" attached to them. Apparently Google decides that if the From: address is yours, then you "sent" the message.

Note that in SMTP there are two "from addresses": the envelope sender (which you don't see) and the "From:" address/header (which you do see) that everyone is familiar with. In most (but not all) legitimate e-mail, they will be the same.

In these cases, your e-mail address is being used in the "From:" and "To:" headers but a different address is being used in the envelope sender (which is the one that the MTA uses).

Google does seem to be checking SPF correctly (i.e., according to RFC, which says to use the envelope sender) -- since (it seems that) the result of check_host should be "softfail" and the RFC says that one "SHOULD NOT" reject a message based on that... but Google apparently logged "pass". Odd.

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ETA: See a comment from ryan-c below about the funky "exists:" mechanism in Telus' SPF record; it explains why check_host() passed.