Is it normal for my fingers to get numb when i sew?

I enjoying sewing and cross stitch, but I've noticed that sometimes the tips of my pointer and middle fingers on both hands occasionally feel numb, like they're falling asleep. I find it strange, since I sometimes sit for hours working on a project before my fingers react as all, and other time it will happen within a few minutes. Since I don't have any other problems associated with the numbness besides feeling strange for a bit, I don't usually think muchof it.

My dad thought I might just be cutting off my circulation, but that didn't make sense to me, since I don't have any problems when I'm knitting or crocheting, where I actually have yarn wrapped around my fingers. Even if that was true, though, I still figured it would be considered normal, as long as my fingertips aren't turning blue or anything of the sort.

Another possibility that occured to me was that it could be attributed to anemia (which is why I included three choices, instead of sticking to the normal yes or no). I don't know if I have it, but I'm getting a blood test to check for it eventually, and I'm aware there are some problems that can be caused by anemia that might not be normal for non-anemics.

Regardless of the answer, I thanks anyone for their opinion!