Cat dry heaving flem(phlegm)

My cat has ben periodcally dry heaving a little flem (phlegm) since about 2pm today. She will eat, dink and moves about. It is as if she tastes something bad then heaves. She is 9 years old, DLH, and fully vaccinated. Her teeth were cleaned about two months ago and her blood ork was fine.

[Aleda M Cheng, D.V.M., C.V.A]

This symptom can have multiple causes from gastritis to hair balls to hyperthyroid disease to indeed having eating something noxious, to foreign body ingestion, etc.  A thyroid test is not always performed during pre-surgical blood work for a dentistry.  If a thyroid test was performed along with her other pre-surgical blood work, and all was normal than obviously you can look elsewhere.  If the problem does not stop by tomorrow than please seek veterinary attention.  Hopefully she may just need gastric protectants and pepcid.