Not necessarily. One could argue my cell phone's signal is in the public when I use it (home or otherwise; it is rather omnidirectional), and the records thereof aren't subject to it the same way as say a search of my phone or my home.

However, in Carpenter v. United States, government entities were found to be in violation of the fourth when accessing historical CSLI records containing the physical locations of cellphones without a search warrant (at least over a period of 7 days or more, if I understood it right). Previously, it was considered fair game under the basis of records technically turned over to a 3rd party.

Then there's United States v. Jones (2012), where it was established a GPS tracking device was attached to a car constitutes a search.

It remains to be seen how Flock will ultimately hold up in court. Although a few cases have popped up, I think it's too early to tell.