Welcome to the HIV forum. There is no need to be embarrassed because you "do NOT (normally) engage in risky sexual behavior" -- since you did not in fact engage in any risky behavior.
The "scientific portion" is that sexual safety with respect to STDs means this and only this: no unprotected vaginal, anal, or oral sex. Hand-genital contact, genital apposition (withing penetration), kissing and the like may carry very small risks for some STDs, such as HPV, herpes, and syphilis -- but so rarely that you really should not be at all concerned. Basically, if a bare penis doesn't get inside your body, you can ignore STDs including HIV.
Here is another thread that discusses some of the biological reasons there was no risk. The important part starts with the follow-up comment dated December 14:
http://www.medhelp.org/posts/show/1119533
So don't worry about this event. Just keep those condoms handy for the times you actually go on to behaviors that might put you at risk for STDs and HIV.
Regards-- HHH, MD