There was a lot of Iranian AA losses in the opening phase of this war. US went town on anything that looked remotely like AA to secure the sky for themselves, and operated with ever-increasing impunity since.
Between advanced ISR, stealth, ECM and stand-off munitions, US has a lot of tools to make the lives of AA crews into a living hell.
It's unclear what happened here exactly. It might be a "straggler" SAM that wasn't destroyed in the strikes, might be US going too aggressively and putting reduced survivability airframes within an area that wasn't sufficiently cleared, might be an Iranian adaptation not unlike the "SAMbushes" seen in Ukraine.
I don't see it as a sign that Iran is somehow reconstituting its AA capabilities though.
