Blood clot has fallen out 40hrs after bottom wisdom tooth extraction. small amount of blood has remained at bottom of extraction site is this normal?

Would expect: your tooth pulling to have some light bleeding over the next 1-2 days, unless you stop eating or drinking. If you continue to seep blood, like oozing, beyond 2 days, then you may need to check for von Willebrand disease, which is a clotting factor deficiency/ genetic defect.

Post extraction: Loosing the healing clot can happen, especially with vigorous chewing or smoking. This can be very painful. So eat a soft diet and no smoking. If you are having bleeding or severe pain call the extracting dentist ASAP.

It is normal: wisdom teeth that have been removed are more likely to develop dry socket. However, practicing good oral hygiene may prevent dry socket. If concerned, see your oral surgeon for post-op eval.

Can be normal!: If you feel no pain or discomfort, it is normal. However, if concerned then give your dentist a quick call.