You are redirected away from Cryptic's links to Paypal and Paypal links back to Cryptic. Each website handles log in rules differently. If you notice you stay logged into your STO account when coming back from PayPal. My experience with Paypal is that as soon as you leave there site they log you out. It is possible that your browser did not preform this code correctly because of a setting or an internet snafu. It is not Cryptic's responsibility that that third party website does not do as it is intended.
Having troubles with Paypal, can not buy more than 500 points at a time, so I went back to Paypal to check on my account, only to find that STO left me logged in. MAJOR security breach! Makes me want to not trust STO with my credit card information.
I should think that simply Logging Out of STO for a second would Break the Paypal Link, then Log back into STO. Problem solved.