Is it possible to get tetanus from a very small wound from pushpin? I was vaccinated past 3 years with small wound

Generally no. If you have been vaccinated against tetanus then you shld be protected from getting tetanus.
Unlikely to be a pbm. Your vaccination within 3 years will protect you from any risk of tetanus. The spores responsible for tetanus can be found anywhere but are more common in the soil.Any break in the skin can be an opporttunity for tetanus spores or other germs to cause problems.Simple wound care at the time is often adequate to avoid problems.