Anyone else experienced getting offered a job right after the behavioral interview?

I had interviewed for the IBM app developer position and I had the first interview, which I got after taking the coding skills assessment. The first interview was just behavioral and spoke on why IBM,

I had interviewed for the IBM app developer position and I had the first interview, which I got after taking the coding skills assessment. The first interview was just behavioral and spoke on why IBM, my strengths and weaknesses, etc. Then weeks later I get an offer letter. I was just really shocked and wanted to know is this something that happens? (This is for an associate position)