2 programs doesn't mean a pattern. i committed to a school because i was 100% certain about it, but i don't think this happening is reason to make a different decision/make it more quickly. i've seen multiple people on draft say they've accepted their offers straight up after seeing the northwestern thing, which feels unadvisable. i think a reasonable first step would be to email people in the department/grad school, and ask if there's any uncertainty. definitely do not make any decisions based on this. it's crazy to do that. maybe i'll eat my words if it does become a pattern, but it isn't one now.