"Worrisome signs" refers to indications or clues that cause concern or worry. It suggests that there are things happening or being observed that might be considered negative, potentially leading to troubling outcomes. Full definition
The current shift back to SUVs that guzzle much more petroleum than other cars, prompted by low gasoline prices, is a more worrisome sign for future climate change. (scientificamerican.com)
But in some quarters, there are worrisome signs of excess. (kpcb.com)
We learned what types of questions doctors want to know when evaluating low back pain, we reviewed the anatomy of the lower back spine, and the more worrisome signs / symptoms that require immediate attention. (scientificamerican.com)