Historians like Josephus seem to relish giving gory details about Herod’s worsening health in his latter years.
Rashy skin. All-over irritation. Cankles. Swollen feet. Bedridden.
Kidney failure. Heart failure. Respiratory failure.
Fluid in the lungs. Palpitations. Convulsions. Hacking cough.
Gangrenous scrotum. Urethra worms. Warts. Sores.
Diagnosis? Diabetes. Scabies. Syphilis.  Result? Extreme paranoia.
All this to say Herod was in rough shape when he received the Magi from the east.
The Magi were likely Parthian advisors—court astrologers and wizards akin to Merlin at King Arthur’s Court. They would have likely traveled with a retinue—guards, assistants, cultural attaches, political advisors, etc. And when they asked Herod ‘where is he who has been born King of the Jews?’ Herod would have perceived a slight both about his birth (he wasn’t Jewish) and about his kingship (which had been awarded to him by his Roman masters).
The Parthian Empire was the chief threat to Roman safety and security during the time of Herod. The Parthians had backed the Jewish bid for independence nearly four decades earlier. The Jews were successful, for a time, until Herod retook Judea for the Romans at the behest of Marc Anthony.
The Parthians would have considered Herod a treacherous adversary, and the Magi would not likely have been welcomed as friends to Herod’s court.
In typical fashion, Herod decides to try and out-slime his enemies, pretending to be their hospitable ally while secretly checking with the priests and scholars to learn if the Magis’ journey had any prophetic validity.  He is reminded of a prophecy concerning the Messiah and bids the Magi a good journey, thinking to ambush and betray them later.
Tomorrow we’ll examine Herod’s poor use of power, but for today I think it’s simply worth noting that our past deeds will come back to haunt us. In Herod’s case, his past betrayal of the Jewish people and their Parthian allies was coming back to haunt him in the form of Magi and Messiah. Herod refused to cop to his sins, instead trying his old tricks again and again, with increasingly poor results.