I believe Box 12 on my W2 is incorrect. What should I do?

Box 12 on W2 has the value $250. I believe this is my employer's contribution towards my HSA. However, according to the account activity, my employer's contribution was $500, which was split into $250 in March and $250 in July. I have not made any contributions.

My questions are -
1. Was this correctly reported? I joined the company in February so I'm not sure if only the latter $250 is supposed to be reported.
2. If this is incorrect, should I request my company for an amended W2 or just make the change under "Did your employer tell you about any other contributions?" in TurboTax.