It's more likely it was just a routine hazardous weather broadcast. They all start with, "Attention all aircraft..." and they're read every hour when conditions dictate.
7110.65 2-6-2 HAZARDOUS INFLIGHT WEATHER ADVISORY SERVICE (HIWAS)
a. Controllers within commissioned HIWAS areas shall broadcast a HIWAS alert on all frequencies, except emergency frequency, upon receipt of hazardous weather information. Controllers are required to disseminate data based on the operational impact on the sector or area of control jurisdiction.
PHRASEOLOGY-
ATTENTION ALL AIRCRAFT. HAZARDOUS WEATHER INFORMATION (SIGMET, Convective SIGMET, AIRMET, Urgent Pilot Weather Report (UUA), or Center Weather Advisory (CWA), Number or Numbers) FOR (geographical area) AVAILABLE ON HIWAS, FLIGHT WATCH, OR FLIGHT SERVICE FREQUENCIES.