Take his compliments on surface value...don't make it mean more than it currently is. Explain to him that you like him but that you're not used to compliments and that you find it hard to take his complements and give them back. Hopefully he can get that and I don't see why he'd be offended, but I wouldn't go in to detail about the BPD. As things come up, give him bits and pieces of info, but it's too early for the whole picture. Plus..you don't know him well, or what types of issues he could have. Everyone has some. We just don't know most people's. Don't push...but if you feel it coming, tell him that things are happening too fast and back away a little to take a breather; a day or two. God, it's hard. I've pushed away almost everyone I ever became friends with, but I wasn't aware I was doing it much of it at the time. You are. You can use that knowledge to prevent it.....hopefully.