I think policy shifted. I think overflights by balloons are routine. See as evidence reporting that the balloon that started this news cycle was number 4 in the past handful of years, but after the media attention a decision was made to have more of a zero tolerance policy
My understanding was that we may have been filtering these objects out as noise of our sensor arrays, and only just started listening more closely for smaller anomalies.
It's possible this balloon traffic has been relatively routine but we are only recently noticing them and responding to them.
