totally normal, sounds like a personality thing to me :)
You know 3 months is when they have a large growth spurt - so they are very hungry. But it is also a large developmental period for them, so he could be pretty distracted as well with all there is to see, and do and explore.
You puttign him into the feeding position could be the cue he needed torealize that not only is the world a fun interesting place - but I'm hungry too!! LOL.
No need to worry :)
I'm on my 3rd breasrfed baby right now, and let me tell you, that even at 8 months - when she is sitting on my thigh nestled into my arm and visually see that I am un hooking my bra, and she can hear that I am offering her milks - she will still sit there and squirm/fuss/cry for that brief 30 seconds. Even if she wasn;t showing any hunger sigsn before, and I had just picked her uip off the floor because *my* boobs felt full and I wanted to nurse her before dinner/driving/chores whatever.
Some babies are just that way. :)
I just try to latch asap so they don;t fuss themselves into a fit. And don;t worry - it gets much much easier as they get older.
Just remeber to offer the breast often to keep up with his growing needs. especially during a growth spurt when they might nurse a whole lot, and then the next week be back to normal, or even less often for a few days.
HTH!