Yes, it's fine to see something between the heatsink fins.
Yes, it's fine to see something between the heatsink fins.
Likely some residual metal remains from the manufacturing process. You might attempt to gently remove it using a toothpick or similar tool to check if it moves. If it does, it's best to extract it before airflow dislodges it, directing it elsewhere where it could cause a short circuit (especially if it's a metal piece). However, if you can't move it and it's tightly stuck—possibly part of a heat fin or bent out of shape—leaving it in place may be acceptable.
Attempted to push it but it doesn't move and I think it's already fixed. I'll leave it as it is.