[airhead969]

Perhaps the few available platelets were all consumed in the act of forming the clot so they registered as low because they were gone?

[burpee]

That would cause systemic problems for the person and almost certain death.

Platelets are filtered out of the blood by the spleen and then stored or cleaned up there. The spleen likely just cleans them up as per instructions from the immune system. On the other side are production problems where your bone marrow stops producing platelets, but that is more commonly due to cancers or cancer treatments.