In february I had an optic migraine. Today I had another- exactly the same- for about 20 min. Should I worry?

No. If you are sure it was a visual (optical or retinal) migraine than you don't need to worry as these are benign. Optical migraines typically presents as visual changes (shimmering, flashes, and/or jagged lines) appearing for 5 to 30 minutes. Unlike a regular migraine these symptoms are not followed by a headache. Other conditions should be excluded like a retinal or a vitreous detachment or tia.
No. Ocular migraines are a form of migraines that take place in the occipital cortex (part of the brain that interprets/controls vision). They lack the severe headache as common migraines. The symptoms are usually all or mostly visual and are typically described as flashing of light or ziz-zag lights in the vision. They usually last less than 30 minutes and affect the vision out of both eyes.
See MD. Retinal migraine (also known ocular migraine) is a retinal disease often accompanied by migraine headache and typically affects only one eye. It is caused by an infarct or vascular spasm in or behind the affected eye. The terms "retinal migraine" and "ocular migraine" are often confused with an abnormal condition in the brain (cortical spreading depression) that may cause similar symptoms.