I think I would do the same, therefore my feeling is that you acted right, probably. I say probably, because it may be something else beside porn, and surfing for porn on a company machine is reckless, which is not a great feature for anybody, especially for a sysadmin. Bottom line, from the human perspective you did good, from your own safety prospective, you could have done better. But I think you already know that.
I think I would do the same, therefore my feeling is that you acted right, probably. I say probably, because it may be something else beside porn, and surfing for porn on a company machine is reckless, which is not a great feature for anybody, especially for a sysadmin. Bottom line, from the human perspective you did good, from your own safety prospective, you could have done better. But I think you already know that.