Interesting story - need advice

So I'm kinda crushing on my best friend (like you've never heard that before lol) and I'm not sure what to do with it. By all outward appearances he is straight as can be but a couple of months ago something happened and since that I've started to think something might be possible between us. I'm not looking for any kind of serious relationship (but if it happened I'd be open) but a fwb thing would be cool. Honestly, I just want him to know the truth about who I am. I've been thinking about coming out to him for a while but I'm so afraid of damaging the friendship that I never have. Lately I've been having a very strong urge to come out to him and what happened has made me consider it more seriously than ever before.I was browsing Grindr a few months ago and got a message from this headless torso. Usually I wouldn't respond but in this case I went ahead and messaged back. We talked for a few before he asked for a dick pic, we swapped and then I asked for a face pic. When he sent me his face pic everything changed. It was my best friend, and I was completely shocked. I stared blankly at my screen and did nothing. To this day he still had no idea it was me he was talking to. This really threw me for a loop because I'd never suspect him of even trying anything gay and because if that I'd more or less resigned myself to the fact that nothing would ever happen. I don't know what to think now.Most of me thinks that he really is straight, or at most heteroflexible. After that encounter he disappeared for a month and then I saw him again. We messaged a few times and then he disappeared again and hasn't been back on since. That's been about another month now. I'm thinking he was just on there because he really wanted to bust a quick nut and maybe thought he'd give it a shot. Maybe I'm just so paranoid about the whole situation I can't see what's really going on.So my questions to you are:Should I come out to him? If so, how? Should I mention seeing him on Grindr? Knowing that I'd welcome a sexual relationship but don't want to damage the friendship, how would you proceed?