The part of your post that’s “unsettling” pun intended, is the time line. The house was built in 2002 and sold in 2013. Ten plus years without a crack and then cracks show up in different locations within 3 months of the sale.
Did you have a home inspection before the sale? Was any repair to mortar noted? Could you have not seen them at purchase and just saw them 3 months later? In looking at your photos if the cracks were surface patched just to get the house sold they did a good job as I can’t see any difference in shade etc.
Unless you can tell us there was an earthquake or rapid freeze or something that happened 3 months after you bought it, my deductive reasoning tells me they have been there a long time and patched over for the sale. If you could get a brick out maybe you could get a clue as to when it happened. If it was covered up you may have a case against the seller.
Just my thoughts from across the country.