Same thing happened to me @ 5 weeks. First of all when a hair falls out and has a little bulb, this is normal...the bulb is the root part and means it is a healthy hair that will grow back (you may have noticed that as your hair loss progressed some hairs have little bulbs, meaning they should've fallen out and others are hair with nothing at the end....these are dead and gone).
I've found that a HUGE misconception is that ALOT of hair that falls out has dead skin around it. Some bubbles up on your scalp like the graft is pushing itself out, some congregates around the graft and falls out with the hair, looking like a graft(I actually had a chunk of skin with 2 hairs running through it, but it wasn't a graft).
At 6 weeks the grafts took. The range I've heard is 7-10 days and they're set. After that for them to fall out, it mostly involves bleeding and ripping them out.
I'm noty sure if you saw your grafts before they put them in, but they look like a small grain of rice with 1,2, or 3(if you have a good doctor) hairs sticking out from both ends....not a hair with a little bulb at the end.
I was worried sick soooo many times for sooooo many reasons and I'm only at 11 weeks but thought my operation was a failuire so many times when it wasn't. I'll bet your fine.