I think most companies roll out OTA updates in stages, so that everyone isn't downloading them at the same time. I guess that would also give them time to respond to issues from early updaters and halt the OTA before everyone gets it (you may have seen before where a company stops an update from going out to everyone after some users experienced bugs).
Still, if you have gotten OTA updates before, and haven't since April... well, that is kinda weird. Thankfully, manually updating is always an option, if a minor inconvenience.