Is it creepy to do an Internet search on a person you meet online and add them on Facebook?

Okay, so I made a friend on this website.  He said that he is willing to be contacted by me outside of the site including via text message and Facebook.  However, he said he was unable to give me his contact information at the time.  Now, the guy said that he is barely on the Internet, and he hasn't logged back on that site in over a week.  I did a Google search of him and managed to find his phone number in the list of the search results.  The search results showed his profile on the site and it said "Hit me up 555-555-5555."  That's obviously not his number; I'm just typing that to protect his privacy and to communicate what I saw, as clearly as possible.  I attempted to search for him using what I believed to be his name.  I found nothing.  I decided to add his number to my phone contacts and I used Facebook to find my contacts on Facebook.  I found the guy's Facebook page, and although I want to add him, I'm scared that he will be offended, think I'm creepy, and I'll lose him as a friend, and he'll feel violated.  One of my friends said that he won't be upset if I add him, and that Facebook is for finding new friends; however, I think that it is poor etiquette to add strangers on Facebook or to add someone without them knowing how they found you and I think that Facebook is for friends you already have and not for the purpose of making new friends.